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HomeMy WebLinkAbout10-15-19 UVBGSA Agenda PacketUKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY 501 Low Gap Rd., Rm. 1010  Ukiah  California 95482  (707)463-4441  fax (707)463-7237 NOTICE OF SPECIAL MEETING NOTICE IS HEREBY GIVEN that the Ukiah Valley Basin Groundwater Sustainability Agency (“Agency”) Board of Directors (“Board”) will hold its regular Board Meeting at: 1:30 P.M. – Tuesday, October 15, 2019 Mendocino County Board of Supervisors Chambers, 501 Low Gap Road, Room 1070, CA 95482 AGENDA 1. CALL TO ORDER AND ROLL CALL 2. PLEDGE OF ALLEGIANCE 3. CONSENT ITEMS a. Approval of Minutes from the September 12, 2019 Meeting b. Appointment of Christopher Watt as Alternate Director Representing the Russian River Flood Control and Water Conservation District 4. STAFF UPDATES 5. PUBLIC COMMENTS ON ITEMS NOT ON THE AGENDA The Board will receive public comments on items not appearing on the agenda and within the subject matter jurisdiction of the Agency. The Board will not enter into a detailed discussion or take any action on any items presented during public comments. Such items may only be referred to staff for administrat ive action or scheduled on a subsequent agenda for discussion. Persons wishing to speak on specific agenda items should do so at the time specified for those items. The presiding Chair shall limit public comments to three minutes. 6. ACTION ITEMS a. Discussion and Possible Action Regarding Proposition 68 Solicitation for Groundwater Sustainability Plan Development and Projects The Board will receive a presentation regarding Proposition 68 funding availability and staff recommendation regarding applying for additional funding to support the development of the Ukiah Valley Groundwater Sustainability Plan. UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY 501 Low Gap Rd., Rm. 1010  Ukiah  California 95482  (707)463-4441  fax (707)463-7237 b. Update, Discussion and Possible Action Regarding the Ukiah Valley Basin Groundwater Sustainability Agency’s Technical Support Services Application The Board will receive an update regarding the Agency’s Technical Support Services application with the Department of Water Resources for monitoring wells. c. Presentation, Discussion and Possible Action Regarding the Hydrogeological Conceptual Model (HCM) Under Development for the Groundwater Sustainability Plan Chapter The Board will receive an update from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan. d. Presentation, Discussion and Possible Action Regarding the Data Management System The Board will receive an update from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan. e. Presentation, Discussion and Possible Action Regarding the Water Budget The Board will receive an update from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan. f. Adoption of a Resolution Authorizing the General Manager of the Mendocino County Water Agency to Apply for the Department of Water Resources Proposition 68 2019 Sustainable Groundwater Management Grant Program Planning – Round 3 Grant on Behalf of the Agency The Board will consider adoption of a Resolution authorizing the Mendocino County Water Agency to submit a Proposition 68 grant application on the Agency’s behalf. 7. DIRECTOR REPORTS UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY 501 Low Gap Rd., Rm. 1010  Ukiah  California 95482  (707)463-4441  fax (707)463-7237 8. ADJOURNMENT The Ukiah Valley Basin Groundwater Sustainability Agency complies with ADA requirements and upon request, will attempt to reasonably accommodate individuals with disabilities by making meeting material available in appropriate alternative formats (pursuant to Government Code Section 54953.2). Anyone requiring reasonable accommodation to participate in the meeting should contact the Mendocino County Executive Office by calling (707) 463-4441 at least five days prior to the meeting. Please reference the Mendocino County website to obtain additional information for the Ukiah Valley Basin Groundwater Sustainability Agency: http://www.mendocinocounty.org/uvbgsa Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 3.a Date: 10/15/19 To: Board of Directors Subject: Discussion and Possible Approval of Minutes from the September 12, 2019 Regular Meeting Consent Agenda Regular Agenda Noticed Public Hearing Summary: Approval of Minutes from September 12, 2019, Regular Meeting. Recommended Action: Approve the September 12, 2019, regular meeting minutes. Background: The Agency convened on September 12, 2019. Fiscal Summary: N/A Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 1 of 1 UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY 501 Low Gap Rd., Rm. 1010  Ukiah  California 95482  (707)463-4441  fax (707)463-7237 1:30 P.M. – September 12, 2019 Mendocino County Board of Supervisors Chambers, 501 Low Gap Road, Room 1070, CA 95482 ACTION MINUTES 1. CALL TO ORDER AND ROLL CALL (1:34 P.M) Present: Director Crane, Director Robinson, Director White, Director Cardoza, Chair Brown 2. PLEDGE OF ALLEGIANCE The Pledge of Allegiance was led by: Chair Brown 3. CONSENT ITEMS 3(a). Discussion and Possible Approval of Minutes from the June 13, 2019 Regular Meeting Presenter/s: Chair Brown Public Comment: None. Board Action: Upon motion by Director Crane, seconded by Director White, and carried (9/12/2019); IT IS ORDERED that the minutes from the June 13th 2019, Ukiah Valley Groundwater Sustainability Agency are hereby approved. 4. STAFF UPDATES Presenter/s: Sarah Dukett Staff gave an introduction of the new clerks, provided by the Department of Planning and Building Services, as well as a notification regarding the change in posting location of the agenda and action minutes. 5. PUBLIC COMMENTS ON ITEMS NOT ON THE AGENDA Presenter/s: None. 6. ACTION ITEMS 6(a) Discussion and Possible Action Regarding Proposition 68 Solicitation for Groundwater Sustainability Plan Development and Projects Presenter/s: Sarah Dukett Public Comment: None. 1 UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY 501 Low Gap Rd., Rm. 1010  Ukiah  California 95482  (707)463-4441  fax (707)463-7237 The Board received a presentation regarding Proposition 68 funding availability and staff recommendation to apply for additional funding to support the development of the Ukiah Valley Groundwater Sustainability Plan. Examples provided by Ms. Dukett, along with plans to come back in October with a final plan from Larry Walker and Associates after maximizing the total amount of funding possible. Board Action: No Board Action taken. 6(b) Update, Discussion and Possible Action Regarding the Ukiah Valley Basin Groundwater Sustainability Agency’s Technical Support services Application Presenter/s: Sarah Dukett Public Comment: None. The Board received an update regarding the Agency’s Technical Support Services application with the Department of Water Resources for monitoring wells. Board Action: No Board Action taken. 6(c) Discussion and Possible Action Changes to the 2019 Board of Directors Master Meeting Calendar Presenter/s: Sarah Dukett Public Comment: None. Staff is coordinating an outreach workshop with the local tribes as part of the Groundwater Sustainability Planning effort. To consolidate travel and expenses staff requested approval to reschedule the regular October 10th meeting for October 17th or 24th, if necessary Board Action: Direction to staff to utilize a Special Meeting, if necessary, to accommodate the tribal meeting and consolidated travel. 7. DIRECTOR REPORTS No reports given. 8. ADJOURNMENT (2:08 P.M.) ________________________________ CARRE BROWN, Chair Attest: ________________________________ 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 3.b Date: 10/15/19 To: Board of Directors Subject: Appointment of Christopher Watt as Alternate Director Representing the Russian River Flood Control and Water Conservation District Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Russian River Flood Control is requesting to replace their alternate Director seat with their Board Member Christopher Watt. Recommended Action: Appoint Christopher Watt as Alternate Director Representing the Russian River Flood Control and Water Conservation District Background: The JPA agreement in section 7.3.1 and 7.4. describes the appointment method for Directors. Attached is a Resolution from Russian River Flood Control appointing Christopher Watt as an Alternate Director. 7.3.1. Member Directors. Each Member Director must sit on the governing board of the Member and be appointed by that governing board by Resolution, which Resolution shall be transmitted to the Secretary of the Agency following adoption by the Member. 7.4. Alternate Directors. Each Member may also appoint one (1) Alternate Director to the Board of Directors, and an Alternate Director shall be appointed for each Stakeholder Director. All Alternate Directors shall be appointed in the same manner as set forth in Section 7.3. Fiscal Summary: N/A Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 2 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.a Date: 10/15/19 To: Board of Directors Subject: Discussion and Possible Action Regarding Proposition 68 Solicitation for Groundwater Sustainability Plan Development and Projects Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will receive a presentation regarding Proposition 68 funding availability and staff recommendation regarding applying for additional funding to support the development of the Ukiah Valley Groundwater Sustainability Plan. Recommended Action: Provide direction to staff regarding the Proposition 68 solicitation for Groundwater Sustainability Plan development and projects. Background: On May 3, 2019, DWR released the Draft SGM Grant Program Proposition 68 2019 Guidelines and Planning Grant - Round 3 Proposal Solicitation Package (PSP) to conduct the third SGM Planning Grant solicitation in mid-May to make approximately $47 million available for competitive grants. The Proposition 68 SGM Implementation Grant solicitation is anticipated to open in early 2020. At least $88 million will be available for competitive grants for projects that address drought and groundwater investments. The Proposition 68 solicitation will be released on September 9, 2019 and will be open for 8 weeks and close in early November. Fiscal Summary: N/A Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 2 of 2 Proposition 68 Grant Application – Scope and Cost Estimate Overview Note: Grant application is under development the estimates are subject to change based on feedback from the Board, TAC and further budget refinement. Category A Grant Management Estimate: $70,800 • Contractor coordination • Grant Agreement amendments or modifications • Quarterly Progress Reports and invoices including budget and schedule updates • Draft and final grant completion report • Coordination and communication with Department of Water Resources • Environmental Information Form Category B Stakeholder Engagement/Outreach Estimate: $313,000 • 4 public meetings (2 in 2020 and 2 in 2021) • Targeted stakeholders meetings (tribal engagement, one on one meetings, Farm Bureau) 12 meetings in 2 years • Targeted meetings with TAC members and board members as needed (8 meetings over 2 years) • Development of targeted material to be distributed by the county • Printing and distribution of materials Category C GSP Development Estimate: $350,000 • Coordination with Sonoma Water and USGS to develop a new model embedded in the model currently developed by USGS. Development of a new MODFLOW groundwater model and of a new Rainfall-Runoff model for the entire watershed (PRMS). This was requested by the TAC as a better representation of surface water flows is critical for development of a successful plan ($250,000) • GSP writing and responding to comments: a new process is under development to develop draft chapters sooner than expected and to better include public comments into the GSP document and this was not budgeted in the previous effort. We believe that providing opportunities to comment at different stages of the GSP development will enhance the reliability of the GSP and will result in a GSP widely endorsed ($100,000) Category C Monitoring/Assessment Estimate: $400,000 • Isotopic Recharge study to analyze surface water samples, well samples and rainfall samples: this will enhance understanding of SW/GW interactions, enhance the hydrogeological conceptual model, delineate primary recharge areas and recharge sources and will be helping in designing future groundwater recharge projects ($150,000) • Install and instruments more transects throughout the Russian river and in some tributaries: the area is very poor of long-term data and instrumenting a good and reliable monitoring network of both surface water and groundwater is critical for demonstrating basin sustainability in the next 20 years. This task may involve drilling new monitoring wells which will complement the new wells approved through TSS ($150,000) • Water Agency: Coordination with DWR on the drilling of wells. Purchasing and installation of equipment. Finalizing land access agreements for well and monitoring equipment. Incorporation of monitoring network in CASGEM program ($24,000) • Geophysical studies: better validation of information provided by borelogs data would help increasing the HCM reliability, will inform selection of new wells site. Some specific studies such as NMR (Nuclear-Magnetic Resistance) in specific areas would significantly improve the understanding of the basin ($100,000) Category C Water Agency Participation and Review of addition grant items Estimate: $39,000 • Participation, comment and review of category C by Mendocino County Water Agency and Ukiah Valley Groundwater Sustainability Agency ($39,000) Total Grant Application Budget Estimate: $1,1196,800 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.b Date: 10/15/19 To: Board of Directors Subject: Update, Discussion and Possible Action Regarding the Ukiah Valley Basin Groundwater Sustainability Agency’s Technical Support Services Application Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will receive an update regarding the Agency’s Technical Support Services application with the Department of Water Resources for monitoring wells. Recommended Action: Provide direction to staff regarding the Department of Water Resources Technical Support Services application. Background: On April 29, 2019, the Department of Water Resources tentatively approved the Agency’s Technical Support Services application to drill monitoring wells in the Ukiah Valley to support the Groundwater Sustainability Plan development and compliance. Due to some of the well locations not being viable and the need to identify new location, the Department of Water Resources has rescheduled Ukiah for spring 2020. Fiscal Summary: N/A Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 1 of 1 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.c Date: 10/15/19 To: Board of Directors Subject: Presentation, Discussion and Possible Action Regarding the Hydrogeological Conceptual Model (HCM) Under Development for the Groundwater Sustainability Plan Chapter Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will receive an update and presentation from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan focusing on the Hydrogeological Conceptual Model (HCM) under Development for the Groundwater Sustainability Plan Chapter. Recommended Action: Provide direction to staff regarding the Hydrogeological Conceptual Model. Background: On June 14, 2018, the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) recommended approval of a contract with Larry Walker and Associates for the development of the Ukiah Valley Groundwater Sustainability Plan (GSP). On July 10, 2018, the Mendocino County Water Agency Board of Directors approved the contract with Larry Walker and Associates. On September 13, 2018, Larry Walker and Associates present an overview of the project and schedule to solicit feedback from the Board. Larry Walker and Associates will be presenting to the Board on a regular basis to review components of the GSP for feedback and approval. Fiscal Summary: N/A Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 2 of 2 Hydrogeologic Conceptual Model Ukiah Valley Basin Groundwater Sustainability Plan DRAFT September 2019 Prepared for: Ukiah Valley Basin Groundwater Sustainability Agency (Replace image w/project photo) DRAFT Hydrogeologic Conceptual Model Ukiah Valley Basin Groundwater Sustainability Plan Prepared for: Ukiah Valley Basin Groundwater Sustainability Agency Prepared by: GEI Consultants 2868 Prospect Park Drive, Suite 400 Sacramento, CA 95670 September 30, 2019 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin i DRAFT HYRDOGEOLOGIC CONCEPTUAL MODEL UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY PLAN Certifications and Seals This report and analysis was prepared by the following GEI Consultants Inc. professionals. Date: Trevor Kent Staff Geologist ________________________ Date: Christian Petersen Principal Hydrogeologist Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin ii DRAFT Table of Contents Table of Contents ..................................................................................................................................................... ii 1. Introduction ..................................................................................................................................... 5 2. Basin Setting ................................................................................................................................... 7 2.1 Basin Boundary ................................................................................................................... 7 3. Soils ................................................................................................................................................. 8 3.1 Hydrologic Soil Groups ........................................................................................................ 8 3.2 Taxonomic Soil Orders ........................................................................................................ 9 4. Regional Geology ......................................................................................................................... 10 4.1 Geologic History ................................................................................................................ 10 4.2 Geologic Formations ......................................................................................................... 10 Quaternary Alluvium ............................................................................................. 11 Terrace Deposits .................................................................................................. 11 Continental Basin Deposits .................................................................................. 11 Franciscan Formation ........................................................................................... 12 4.3 Faults and Folds ................................................................................................................ 12 Maacama Fault ..................................................................................................... 12 4.4 Geologic Cross Sections ................................................................................................... 12 Cross Section Development ................................................................................. 13 Cross Section Interpretation ................................................................................. 14 5. Principal Aquifers and Aquitards................................................................................................ 18 5.1 Aquifer I – Quaternary Alluvium ........................................................................................ 19 5.2 Aquifer II – Terrace Deposits ............................................................................................. 20 5.3 Aquifer III – Continental Basin Deposits ............................................................................ 21 5.4 Aquifer Water Quality ........................................................................................................ 22 5.5 Aquitards............................................................................................................................ 23 5.6 Beneficial Users ................................................................................................................. 24 6. Groundwater Recharge and Flow ............................................................................................... 26 6.1 Groundwater Flow Direction and Gradient ........................................................................ 26 6.2 Recharge Areas ................................................................................................................. 27 6.3 Discharge Areas ................................................................................................................ 27 7. Surface Water ............................................................................................................................... 28 7.1 Surface Water Characterization ........................................................................................ 28 Water Systems Operations .................................................................................. 32 7.2 Groundwater – Surface Water Interaction ......................................................................... 33 8. Data Gaps ...................................................................................................................................... 34 9. References .................................................................................................................................... 35 Appendix A. LACO Initial Hydrogeologic Conceptual Model ......................................................................... 59 Appendix B. DWR Hydrogeologic Conceptual Model BMP ............................................................................ 60 Appendix C. Cross Section Well Logs ............................................................................................................. 61 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin iii DRAFT Figures Figure 1: Basin Setting ............................................................................................................................................. 38 Figure 2: Hydrologic Soils Groups ............................................................................................................................ 39 Figure 3: Taxonomic Soil Orders .............................................................................................................................. 40 Figure 4: Surficial Geology ....................................................................................................................................... 41 Figure 5: Well and Cross Section Locations ............................................................................................................ 42 Figure 6: Cross Section A-A' with Well Locations .................................................................................................... 43 Figure 7: Cross Section B-B' and C-C' with Well Locations ..................................................................................... 44 Figure 8: Cross Section A-A' .................................................................................................................................... 45 Figure 9: Cross Section B-B' .................................................................................................................................... 46 Figure 10: Cross Section C-C' .................................................................................................................................. 47 Figure 11: Open GeoTracker Sites ........................................................................................................................... 48 Figure 12: Basic Groundwater Hydrology Paper 2220 - Conductivity Values .......................................................... 49 Figure 13: Groundwater Recharge and Flow ........................................................................................................... 50 Figure 14: CASGEM Hydrograph Wells ................................................................................................................... 51 Figure 15: UVGB North Hydrograph ......................................................................................................................... 52 Figure 16: UVGB Central Hydrograph ...................................................................................................................... 53 Figure 17: UVGB South Hydrograph ........................................................................................................................ 54 Figure 18: Available Streamflow Measurement Gauges within the UVGB .............................................................. 55 Figure 19: Mean Annual Streamflow at Select Stations ........................................................................................... 56 Figure 20: Mean Daily Streamflow; Station 11462500 Russian River North of Hopland ......................................... 56 Figure 21: Mean Daily Streamflow; Station 11462000 East Fork Russian River ..................................................... 57 Figure 22: Mean Daily Streamflow; Station 11461000 Russian River North of Ukiah ............................................. 57 Figure 23: Proposed Groundwater/Surface Water Monitoring Network ................................................................... 58 Tables Table 1: SGMA Cross-Reference Table ..................................................................................................................... 6 Table 2: Lithologic Codes for Cross Sections .......................................................................................................... 13 Table 3: Regional Cross Section Characteristics ..................................................................................................... 17 Table 4: Aquifer Characteristics ............................................................................................................................... 18 Table 5: Principal Aquifer I - Pump Test Data .......................................................................................................... 20 Table 6: Principal Aquifer II - Pump Test Data ......................................................................................................... 21 Table 7: Principal Aquifer III - Pump Test Data ........................................................................................................ 22 Table 8: Principal Aquifer I - Water Quality .............................................................................................................. 23 Table 9: Primary Groundwater Use by Principal Aquifer .......................................................................................... 24 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 4 DRAFT List of Acronyms BMP ........................................... Best Management Practice cfs............................................... cubic feet per second CGS ........................................... California Geological Survey CLSI ........................................... California Land Stewardship Institute CASGEM ................................... California State Groundwater Elevation Monitoring DWR .......................................... Department of Water Resources ft ................................................. feet GEI ............................................ GEI Consultants Inc. gpm ............................................ Gallons per minute GSA ............................................ Groundwater Sustainability Agency GSP ............................................ Groundwater Sustainability Plan HCM .......................................... Hydrogeologic Conceptual Model IHCM ......................................... Initial Hydrogeologic Conceptual Model LACO ......................................... LACO Associates LUST .......................................... Leaking Underground Storage Tank LWA ........................................... Larry Walker and Associates MCWA ....................................... Mendocino County Water Agency msl ............................................. mean sea level NMFS ......................................... National Marine Fisheries Service NRCS ......................................... Natural Resources Conservation Service PG&E ........................................ Pacific Gas and Electric Qal ............................................. Quaternary Alluvium Qt ............................................... Terrace Deposits QTub .......................................... Continental Basin Deposits KJf ............................................. Franciscan Formation SGMA ........................................ Sustainable Groundwater Management Act SSURGO .................................... Soil Survey Geographic Database SWRCB ...................................... State Water Resources Control Board UVGB ........................................ Ukiah Valley Basin USACE ....................................... United States Army Corps of Engineers USGS ......................................... United States Geological Survey WCR ........................................... Well Completion Report Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 5 DRAFT 1. Introduction This Hydrogeologic Conceptual Model (HCM) has been developed by GEI Consultants (GEI) for the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) for inclusion in the Groundwater Sustainability Plan (GSP) under the requirements of the Sustainable Groundwater Management Act (SGMA). The purpose of this HCM is to meet the regulatory requirements mandated by SGMA along with establishing a framework hydrogeologic model with which to guide development of the GSP and management of the basin, including future modeling efforts and monitoring programs. Requirements of an HCM under SGMA Regulations Chapter 1.5, Article 5, Subarticle 2: 354.14, and sections of this document that meet said requirements, are found in Table 1. The HCM describes the basin setting, general geology, hydrology, and hydrogeology of the basin. Organization of the HCM is as follows: 1. Basin Setting: Description of the geographic setting, topography, climate, and general hydrology of the basin. Identifies basin boundaries and public entities within the basin. 2. Soils: General soil types found throughout the basin and their general location. Broken into hydrologic and taxonomic groups. 3. Regional Geology: Geologic formations found throughout the basin, and their descriptions, along with major geologic structures. Development and discussion of three cross sections within the UVGB. 4. Principal Aquifers and Aquitards: Major aquifers, water bearing formations, and aquitards within the basin. Regional hydrogeologic characteristics. 5. Groundwater Recharge and Discharge: Regions of significant recharge to the basin’s groundwater supply and understanding of the flow of groundwater through the basin. 6. Surface Water: Surface water characteristics, flow, and infrastructure within the basin. Groundwater and surface water interactions and monitoring. Sources and infrastructure for imported water supply. 7. Data Gaps: Significant gaps in the understanding of the basin groundwater and surface water characteristics. Development of the HCM was based primarily on the Initial Groundwater Sustainability Plan Hydrogeologic Conceptual Model (IHCM) (LACO, 2017) by LACO Associates (LACO), provided in Attachment A, and informed by the Department of Water Resources’ (DWR’s) HCM Best Management Practices (BMP) document (DWR, 2016) provided in Attachment B. The literature review and analysis done under the IHCM provided the foundation for this updated HCM. Data collected and analyzed under the IHCM were used for this HCM and supplemented with available data from public entities, such as the CASGEM and GeoTracker programs, where applicable. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 6 DRAFT Table 1: SGMA Cross-Reference Table SGMA Section Requirements HCM Chapter a Each Plan shall include a descriptive Hydrogeologic Conceptual Model of the Basin based on technical studies and qualified maps that characterizes the physical components and interaction of the surface water and groundwater systems in the basin. X b The hydrogeologic conceptual model shall be summarized in a written description that includes the following:X 1 The regional geologic and structural setting of the basin including the immediate surrounding area, as necessary for geologic consistency 2, 2.1, 4 2 Lateral basin boundaries, including major geologic features that significantly affect groundwater flow 2, 2.1, 4.3.1 3 The definable bottom of the basin 2.1 4 Principal aquifers and aquitards, including the following information 5 A Formation names, if defined 5.1, 5.2, 5.3 B Physical properties of aquifers and aquitards, including the vertical and lateral extent, hydraulic conductivity and storativity, which may be based on existing technical studies or other best available information 5.1, 5.2, 5.3, 5.5 C Structural properties of the basin that restrict groundwater flow within the principal aquifers, including information regarding stratigraphic changes, truncation of units, or other features 4.3.1, 5.3, 5.5 D General water quality of the principal aquifers, which may be based on information derived from existing technical studies or regulatory programs 5.1.1, 5.2.1, 5.3.1, 5.5 E Identification of the primary users or uses of each aquifer, such as domestic, irrigation, or municipal water supply 5.5 5 Identification of data gaps and uncertainty within the hydrogeologic conceptual model 8 c The hydrogeologic conceptual model shall be represented graphically by at least two scaled cross-section that display the information required by this section and are sufficient to depict major stratigraphic and structural features in the basin 4.4, 4.4.1, 4.4.2 d Physical characteristic of the basin shall be represented on one or more maps that depict the following X 1 Topographic information derived from the U.S Geological Survey or another reliable source 2, 2.1, Figure 1 2 Surficial geology derived from a qualified map including the locations of cross- sections required by this Section 4.2, Figure 4, Figure 5 3 Soil characteristics as described by the appropriate Natural Resources Conservation Service soil survey or other applicable studies 3, 3.1, 3.2, Figure 2, Figure 3 4 Delineation of existing recharge areas that substantially contribute to the replenishment of the basin, potential recharge areas, and discharge areas, including significant active springs, seeps, and wetlands within or adjacent to the basin 6, Figure 9 5 Surface water bodies that are significant to the management of the basin 7.1, Figure 10 6 The source and point of delivery for imported water supplies 7.3, Figure 11 Notes: X, Section addressed by HCM in its entirety Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 7 DRAFT 2. Basin Setting The UVGB underlies the Redwood Valley and Ukiah Valley, along with their tributary valleys, in Mendocino County, California. It is approximately 22 miles long and 5 miles wide at its widest point with a total area of 37,500 acres. Groundsurface elevation of the basin ranges from approximately 500 feet mean sea level (msl) in the south to 1,000 feet msl in the north (DWR, 2004). USGS topographic data along with location and extent of the UVGB are shown in Figure 1. The UVGB is bounded on all sides by the Coastal Ranges, primarily the Mendocino Range (Farrar, 1986). Highway 101 runs the entire length of the basin and connects with Highway 20, which enters the basin from the east, at Calpella (DWR, 2004). Cities within the UVGB include Calpella, Ukiah, and Talmage with Ukiah being the largest in the basin. The Russian River, and its tributaries, along with Lake Mendocino are the major surface water features within the basin. The Russian river runs through the entire length of the basin with many smaller tributaries contained within the UVGB. Lake Mendocino is located on the eastern side of the basin and the east fork of the Russian river enters the basin just south of the lake. Annual precipitation in the basin ranges from 45 inches in the north to 35 inches in the south (DWR, 2004). 2.1 Basin Boundary The UVGB basin boundary is identified in the 2018 update to DWR’s Bulletin 118 (DWR, 2004, 2018) as basin 1-052 within the North Coast hydrologic region. The basin bounded by the Mendocino Range of the Coastal Ranges which is composed primarily of the Franciscan Complex bedrock (Franciscan formation). To the south, the UVGB is bordered by the Sanel Valley Groundwater Basin (1-053). Sanel Valley Groundwater Basin and the UVGB are seperated just north of Hopland by low hills which the Russian River has cut a narrow gorge (Farrar, 1986). In the IHCM, inaccuracies in the Bulletin 118 basin boundary near Lake Mendocino, Robinson Creek, and McNabb Creek were identified. A proposed update to the basin boundary was presented in the IHCM. In this HCM, the boundary presented by Bulletin 118, shown in Figure 1, is used because an update to the boundary description has not been completed. The bottom of the UVGB is defined by the contact with the Franciscan formation. Depth to the Franciscan formation varies throughout the valley. For this HCM, depth to Franciscan formation was based on a Master’s thesis submitted to Humboldt State University titled Evoution of an Intermontane Basin Along the Maacama Fault, Little Lake Valley, Northern California (Erickson, 2008). In this thesis, depth to the Franciscan was based on a gravity study developed using a LaCoste Romberg model G gravity meter G425 to record gravitational anomolies. A total of 465 locations were surveyed and tied into an existing gravity network. Results were then adjusted to the International Gravity Standardization Network 1971 (IGSN-1971) gravity datum and constrained based on data from the Department of Water Resources (DWR) well completion reports. The Erikson study covered the northern portion of the UVGB up to just south of Lake Mendocino. Depth to bedrock in the remainder of the basin was inferred in the IHCM using well completion reports (WCR’s) and gradients established in the Erickson study. Results from the IHCM and Erikson study are used for this HCM and additional well logs have confirmed results from these two studys at select locations. The basin is bounded on the sides by the Francsican formtion of the Mendocino range and it was inferred that the valley fill is in depositional contact with shallow dipping bedrock on the valley margins (Erickson, 2008). Depth to bedrock (Franciscan) is shown on the IHCM cross sections, A-A’, B-B’ and C-C’ with greatest depths to bedrock being 1,950 feet, 1,350 feet, and 1,000 feet, respectively. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 8 DRAFT 3. Soils Soils within the Ukaih Valley Basin were analyzed based on two categories: hydrologic soil groups and taxonomic soil orders. Hydrologic soil groups describe soils ability to transmit water under saturated conditions while taxonomic soil orders describe general properties and origins of a soil. 3.1 Hydrologic Soil Groups The NRCS Hydrologic Soils Group classifications (NRCS, 2012) provide an indication of soil infiltration potential and ability to transmit water under saturated conditions. Hydrologic soil groups are developed based on saturated hydraulic conductivities of shallow, surficial soils. Each group has an associated range with higher conductivities (greater infiltration) in Group A and lower conductivities (lower infiltration) in Group D. Hydrologic soil groups are defined below: • Hydrologic Group A – “Soils in this group have low runoff potential when thoroughly wet. Water is transmitted freely through the soil” (NRCS 2012). Group A soils have high infiltration rates due to well drained sands or gravelly sands and have the highest permeability and recharge potential. • Hydrologic Group B – “Soils in this group have moderately low runoff potential when thoroughly wet. Water transmissiion is unimpeded” (NRCS 2012). Group B soils are moderately well drained due to moderately fine to coarse textures. They have the second highest potential permeability and recharge potential among the soil groups. • Hydrologic Group C – “ Soils in this group have moderately high runoff potential when thoroughly wet. Water transmission is somewhat restricted” (NRCS 2012). This group has restricted potential to contribute to groundwater recharge. Group C soils have low infiltration rates due to their fine texture or because of a layer that impedes downward movement of water. • Hydrologic Group D – “Soils in this group have high runoff potential when thoroughly wet. Water transmission is very restricted.” (NRCS 2012). This group has a very limited capacity to contribute to groundwater recharge. Dual hydrologic groups (A/D, B/D, C/D) are assigned to characterize runoff potential under drainied and undrained conidtions. The first letter represents runoff potential under drained conditions and the second letter is for undrained conditions. Hydrologic soil groups are presented in Figure 2. High infiltration soils, Group A, are located primarily in small bands along the rivers. Moderate infiltration soils, Goup B, occupy the majority of the basin and are primarily in the central portion of the basin. Slow infiltration soils, Group C and Group D, occupy the northern and southern portions as well as the eastern edge of the basin. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 9 DRAFT 3.2 Taxonomic Soil Orders Taxonomic soil orders are presented in Figure 3. Taxonomic orders were identified using the SSURGO database from the NRCS. A total of 5 taxonomic orders are present within the UVGB. Soil orders within the basin, along with descriptions from the NRCS publication Keys to Soil Taxonomy (NRCS, 2014), include: • Alfisol – Strongly weathered mineral soils. Most often, Alfisols develop under native deciduous forests or in some cases, such as California, under savannas (mixed trees and grass). They are characterized by a subsurface horizon in which silicate clay has accumulated through illuviation. • Entisol – Weakly developed mineral soils. Entisols show little to no development of soil horizons. Within the UVGB these soils are likely recently deposited alluvium. • Inceptisol – Weakly developed mineral soils. Inceptisols have very little soil development but are distinguished from Entisols by evidence of a soil horizon. • Mollisol – Formed primarily through the accumulation of calcium-rich organic matter. Characterized by a thick humic (organic) horizon. Contian swellling type clays and a granular/crumb structure. • Vertisol – Identified by shrink swell clays. They are formed through continued shrinking and swelling during wet and dry periods. Most Vertisols are dark and even black in color. They typically develop from limestone, basalt, or other calcium- and magnesium- rich parent material. The most prominent soils groups within the UVGB include Mollisols and Incepetisols. Mollisols are found throughout the basin and primarily along the lowlying middle of the basin where vegetation and clays are present. Incpetisols are found primariy in the foothills or highlands. Younger Enitsols are found along the river channels and likely associated with young alluvial deposits. Alfisols and Vertisols are found in small patches scattered throughout the basin. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 10 DRAFT 4. Regional Geology The UVGB is located mostly within the Mendocino Range in the northern part of the Coast Ranges Geomorphic Province (Farrar, 1986; DWR, 2004). The Mendocino Range is predominantly composed of the thick, late Mesozoic and Cenozoic sedimentary rocks of the Franciscan formation. The Coast Ranges Geomorphic Province exhibits low northwest-trending sub-parallel mountain ranges and valleys resulting from the compressional deformation between the Pacific and American plates (Fuller, 2015). Locally, the topography is controlled by tectonic activity associated with the right-lateral Maacama Fault, a member of the San Andreas Fault System. As shown in Figure 4, this local faulting is expressed in numerous north-west trending lineaments throughout the UVGB (Farrar, 1986). Sediments within the UVGB are formed from erosion of the Franciscan formation and deposition via tectonic activity and upload or as alluvial sediments from stream channel erosion (Farrar, 1986). The following sections detail the geologic history, significant geologic formations, geologic structures (faults and folds), and development of cross sections for the completion of this HCM. 4.1 Geologic History The geomorphology, structural geology and geologic formations of the Coast Ranges occurred as a result of tectonic activity between the continental North American Plate and the oceanic Farallon Plate. During the Mesozoic Era subduction and under thrusting of the Juan De Fuca Plate (a remnant of the Farallon Plate) beneath the North American Plate formed an oceanic trench at the plate boundary. Tectonically mixed sediment accumulated as the trench uplifted and created the mountainous terrain of the Franciscan formation (Farrar, 1986). The Maacama fault formed 3.2 million years ago as a splay of the Roger’s Creek Fault Zone. Several strike slip basins were formed concurrently with the Maacama fault (McLaughlin et al, 2012). The development of such basins is believed to have begun less than 4 million years ago (Farrar, 1986). Formation of the Ukiah Valley was a result of oblique pull apart extension of en echelon and minor branching faults of the Maacama fault system (Farrar, 1986). Right lateral strike-slip motion along parallel faults caused wrenching apart and down dropping of the crustal block, forming a graben. Bounded by faults, as the graben continued to drop a considerable amount of sediment was deposited in the valley (Farrar, 1986). This sediment makes up a good portion of the valley fill seen today. Changes in basin geometry and fault geometry at this point are likely due to adjustments of fault zone reorganization caused by the migration of the Mendocino Triple Junction and the northward movement of a major releasing bend in the San Andreas Fault (McLaughlin et al, 2012). 4.2 Geologic Formations Geologic formations described are based on a literature review including Geology and Ground Water in Russian River Valley Areas and in Round, Laytonville and Little Lake Valleys, Sonoma and Mendocino Counties, California (Cardwell , 1965), Ground-water Resources in Mendocino County, California (Farrar, 1986), Water Supply Assessment for the Ukiah Valley Area Plan (Mendocino County Water Agency, 2010), DWR’s Bulletin 118 basin descriptions (DWR, 2004), the 2005 surficial geology map by Larsen and Kelsey (Larsen and Kelsey, 2005) and local well logs. Four significant geologic formations were identified and are shown in Figure 4. Figure 4 is based on the 2005 Larsen and Kelsey Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 11 DRAFT map which was developed for the UVGB in conjunction with the USGS and DWR. Within the unconsolidated to loosely consolidated valley fill three formations were identified: Quaternary (Recent) Alluvium, Pleistocene Terrace Deposits, and Pliocene/Pleistocene Continental Basin Deposits. Beneath the valley fill material is the Franciscan Formation which makes up the basement and bedrock for the basin. While the Franciscan Formation is not considered to be part of the basin as it pertains to SGMA, it is significant with regards to modeling the behavior of groundwater in the basin and defining the basin bottom. For these reasons, it is included in this HCM. The following sections describe the geologic formations of the UVGB in detail. Quaternary Alluvium Quaternary Alluvium is the primary water producing geologic unit in the UVGB. It consists of unconsolidated gravel, sand, silt, and minor amounts of clay that were deposited in thin bands along river channels and wider flood plains of the Russian River and its tributaries, along with alluvial fans and as colluvium (Cardwell, 1965). These are the non-cemented, youngest, and least weathered of the valley fill geologic units. The thin layers of loose sand and gravel found closest to the Russian River have shown a hydraulic connection with the river. Buried channels of Quaternary Alluvium show coarser material with boulders and gravel (Cardwell, 1965). Alluvium particle size tends larger and coarser along the axis of the stream and finer moving away to the flood plains. However, alluvium is generally heterogeneous with depth at all locations due to the ever-changing nature of river channels (Farrar, 1986). Thickness of the Quaternary Alluvium varies from 10 feet to greater than 100 feet in some places and overlies the Terrace and Continental Basin Deposits (Cardwell, 1965; Farrar, 1986). Terrace Deposits Terrace Deposits are Pleistocene in age and composed of partially to loosely cemented beds of gravel, sand, silt, and clay. They are similar in composition to Continental Basin Deposits but with less silt and clay. Terrace Deposits are discontinuous and long, narrow, elevated, gently inclined surfaces that are laterally interfingered with neighboring beds. Aggradation of eroded material, most likely from the surrounding Franciscan formation, formed the Terrace Deposits (Farrar,1986). These deposits can be broken into two types, older Terrace Deposits and younger Terrace Deposits. Older Terrace Deposits are thin and generally not water bearing. Located in the higher portions of the basin, they consist of red, gravelly clay soil. Younger Terrace Deposits are located lower in the valley and consist of sandy or silty gravel with fragments of cobbles. Beds are compact and nearly flat-lying and may be up to 200 feet thick (Cardwell, 1965). Continental Basin Deposits Continental Basin Deposits are Pliocene and Pleistocene in age and underlie the Quaternary Alluvium and Terrace Deposits. They are comprised of poorly consolidated and poorly sorted clayey and sandy gravel, clayey sand, and sandy clay (Farrar, 1986). The vertical distribution of the Continental Basin Deposit materials includes thick clay layers that lie over and below confined aquifers consisting of sands and gravels (MCWA, 2010). Clays can occur both as beds, several tens of feet thick, to interstitial material between sand and gravel. The high clay content in the formation results in low permeability and low producing wells (MCWA, 2010). Depositional environment for the Continental Basin Deposits consists of weathered Franciscan Formation deposited as alluvial fans and as flood plain, stream channel, and lake bed sediments (Cardwell, 1965). According to Farrar, no wells have fully penetrated the Continental Basin Deposit formation in the UVGB (Farrar, 1986). Continental Basin Deposits Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 12 DRAFT thickness ranges to a depth of up to 2,000 feet along the axis of the valley floor and overlie the basement rock of the Franciscan formation. Franciscan Formation The Franciscan Formation consists of rocks from the Jurassic to Cretaceous age and are considered the basement and bedrock for the basin along with comprising the majority of the surrounding Mendocino Range. It is composed of consolidated marine rocks, sandstone, siltstone, shale, chert, serpentine, greenstone, and schist. Rocks are generally fractured and with numerous faults and zones of shearing (Cardwell, 1965). Fracturing in the Franciscan formation is due to faulting from active plate motion between the North American Plate and Oceanic Plate. 4.3 Faults and Folds Major geologic structures in the UVGB have a regional northwest to north-northwest trend (including faults and folds) which can be observed in topographic features including the Russian River and the axis of the UVGB. However, locally much of the geology shows a chaotic structure (Farrar, 1986). Little evidence of significant folds was observed in investigations of the UVGB but does not exclude the existence of such folds. The Maacama fault is the major fault in the area and runs through the middle of the UVGB trending in a northwest direction. The location of the Maacama fault in the UVGB is shown on Figure 4. Maacama Fault The Maacama fault is a member of the San Andreas fault system and is the result of the interaction between the Pacific, Gorda-Juan de Fuca, and North America plate boundaries. The fault was formed 3.2 million years ago and originated as a northeast splay from the southern portion of the Roger’s Creek Fault Zone (McLaughlin et al. 2012). It displays right lateral motion and from extension, volcanism, and strike-slip basin development, has acquired several right steps and splays during its evolution (Rexford, 1989; McLaughlin et al, 2012). The Maacama fault is mapped as an active fault by the California Geologic survey and may have been active during the Holocene time period (CGS, 2017; Rexford, 1989). Evidence of the Maacama Fault’s effects on groundwater levels and flow were not found during the development of this HCM and will need to be addressed through later studies. 4.4 Geologic Cross Sections Three cross sections were constructed for the development of the HCM to illustrate the subsurface and better understand the hydrogeology of the UVGB. Cross sections were based on previous cross sections done as part of the LACO IHCM and developed at the same locations, shown on Figure 5, to supplement the information presented in the IHCM. IHCM cross sections used well construction reports (WCRs) to show contacts and extent of the geologic formations presented in Section 4.2. They extend down to the assumed basin bottom, or depth to the Franciscan Formation and present a conceptualized look at the layering of the UVGB. These cross sections can be found as part of the IHCM included as Attachment A. For this HCM, textural cross sections were developed that show the subsurface in terms of gravels, sands, silts, and clays rather than geologic units. Textural cross sections provide an improved understanding of how water flows through the subsurface, illustrating the thickness and extent of major aquifers and aquitards. Cross sections were developed only for depths in which subsurface lithology, from WCRs, were available. For this reason, the textural cross sections are shallower than IHCM cross sections, which do show depth to bedrock. Textural cross sections are shown on Figure 6 through Figure 8 and WCRs used for development of the cross sections can be found in Attachment C. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 13 DRAFT Cross Section Development Cross sections were developed using lithologic information from both DWR WCRs and additional well information from the USGS. WCRs from the IHCM cross sections were used where possible to maintain consistency with previously developed cross section in the UVGB. Any identified data gaps from the IHCM cross sections were addressed through the inclusion of wells and borings from the USGS. Well data was then plotted and those wells located reasonably close to each cross section were selected. Selected wells are located no further than 2,500 feet from any cross section with most wells falling within 1,000 feet. Selected wells were projected at ground surface along the appropriate cross sections. Once wells were selected, driller’s logs and WCRs were reviewed with the logged soils descriptions assigned a lithologic code. These lithologic codes were based on the Unified Soil Classification System (USCS). The USCS classifies soils based on dominant texture classes of gravels, sands, silts, and clays. Modified lithologic codes in addition to those of the USCS were used, such as cemented sands and gravels, based on an understanding of the local geology and literature reviews in order to better characterize the subsurface geology. Wells and lithologies were then plotted along the cross sections with the subsurface interpreted by GEI geologists based on well log lithologies, literature reviews, and understanding of the depositional environment for the UVGB. Location of cross sections are shown on Figure 5 with cross sections and well logs used to develop cross sections are shown in Figure 6 and Figure 7. Lithologic codes used for generation of the cross sections, along with geologic formation, hydrogeologic properties, and associated principal aquifers assigned for the HCM, can be found in Table 2. Table 2: Lithologic Codes for Cross Sections From the USGS classifications and the WCRs lithologic descriptions, geologic formations and principal aquifer designations were assigned. Sands and gravels that showed little weathering or cementation were indicative of the younger Quaternary Alluvium. Where these soils were encountered was considered the extent of Principal Aquifer I. Gravels and sands intermixed with fines such as silts and clays, or showing signs of weathering and cementation, were classified as the Terrace Deposits. These deposits are difficult to distinguish from those of the underlying Continental Basin Deposits but where identified were considered the extent of Principal Aquifer II. Terrace Deposits were not identified across all cross sections. Clays sandy/gravely clays, and highly weathered and cemented sands and gravels were classified as Continental Basin Deposits. The major indicator for the Continental Basin deposits were the high clay content or cementation. The clay layers generally signified a transition from the Lithologic Code Description Assigned Geologic Formation Assumed Hydrogeologic Properties Principal Aquifer GP Poorly Graded Gravel Quaternary Alluvium High conductivity I GP*Cemented Gravel Terrace Deposits Moderate to low conductivity II GC Gravel with fines, clayey gravel Continental Basin Deposits Moderate to low conductivity III GC*Cemented Gravel Clay Continental Basin Deposits Moderate to low conductivity III SP Poorly graded sand Quaternary Alluvium High conductivity I SW Well graded sand Quaternary Alluvium High conductivity I SM Sand with fines, silty sand Terrace Deposits Moderate conductivity II SP*Cemented sand Terrace Deposits Moderate conductivity II SC Sand with fines, clayey sand Terrace Deposits Moderate to low conductivity III ML Inorganic silt Terrace Deposits Moderate to low conductivity II Cl Clay Continental Basin Deposits Low conductivity III XLN Crystalline rock Franciscan Formation Low conductivity NA Note: NA - Not Applicable, not considered part of Ukiah Valley Groundwater Basin * Denotes cemented material Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 14 DRAFT Quaternary Alluvium or Terrace Deposits to the Continental Basin Deposits. Where these deposits were identified was considered the extent of Principal Aquifer III. HCM cross sections were referenced against those generated as part of the IHCM. Boundaries between the Quaternary Alluvium and Continental Basin Deposits were compared as well as the general extent of each formation. Franciscan Formation extent was taken from the IHCM cross sections and verified by the inclusion of select USGS wells. Cross Section Interpretation Textural cross sections graphically illustrate the extent of coarse-grained and fine-grained material throughout the basin and are helpful in understanding basin hydraulics and groundwater flow. Based on the lithologic descriptions, coupled with local geology, inferences can be made into the extent and locations of principal aquifers, as well. Cross sections developed as part of this HCM were reviewed to identify the general flow of groundwater through the basin, regions with the most probability of significant groundwater supply, and location and extent of geologic formations/principal aquifers (discussed in Section 5). Geologic formations were identified based on lithologic descriptions, as shown in Table 2. The IHCM was also reviewed to establish depth to bedrock and as a check against the textural cross sections in terms of the location and the extent of the Quaternary Alluvium. Since Terrace Deposits were combined with the Continental Basin Deposits or Quaternary Alluvium the IHCM cross sections were not considered in delineating the Principal Aquifers but rather as a check of location. Both the IHCM and textural cross sections provide a small-scale snapshot of the basin geology at each location, and while regional trends may be inferred, subsurface geology varies as one moves away from the cross sections. Cross Section A-A’ Cross Section A-A’, Figure 8, is the northernmost cross section in the UVGB as shown in Figure 5 and Figure 6. From the textural cross sections, we see that there is little high permeability material (gravels and sands) associated with the Quaternary Alluvium. Loose gravels and sands begin to appear around the western portion of the basin at ground surface near the Russian River. Alluvium material is present at the scale of tens of feet thick and occurs over 3,000 to 4,000 feet wide. This material is likely directly connected to the Russian River due to its proximity. There is no evidence of Quaternary Alluvium outside of this small band of material. Directly adjacent to the Quaternary Alluvium are cemented gravel and sand interlayered with sections of clay and gravel clays. This material is likely indicative of the Terrace Deposits. While significantly less permeable, no barrier to groundwater flow was observed between the Quaternary Alluvium and the two layers are likely connected hydrogeologically. The Terrace Deposits occupy the first 100-200 feet of the cross section. At depth, there are pockets of cemented sands and gravels that are likely evidence of ancient buried stream channels. The deepest well logs, greater than 200 feet deep, show predominantly clay material intermixed with pockets of gravel and sands indicative of the Continental Basin Deposits. To the west, there is evidence for greater sandy clays and gravelly clays in contrast to the clay dominant material to the east. Based on the nature of the Terrace Deposits and Continental Basin Deposits, it is difficult to distinguish between the two material. However, extensive clay layers are assumed to be from the Continental Basin Deposits Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 15 DRAFT and serve as the line of demarcation between the two layers. The large clay layers of the Continental Basin Deposits act as a barrier to groundwater flow with the overlying Terrace Deposits and Quaternary alluvium, creating confined conditions for wells drilled in this layer. Based on the textural cross section for A-A’, it is expected that the greatest amount of available groundwater and flow occurs in the narrow and shallow band of loose sand and gravel along the Russian River. This material is hydrogeologically connected with the cemented sands and gravels of the Terrace Deposits directly adjacent but the significant difference in expected conductivities between the two material may limit groundwater flow between the two. The majority of the subsurface however is intermixed clay and sandy/gravely clays of the Continental Basin Deposits that have low conductivity and limit the flow of groundwater. The IHCM A-A’ (Appendix A) cross section shows greatest depth of the bedrock (Franciscan) contact at an elevation of approximately -1,200 feet mean sea level (msl). Vertical offset of approximately 100 feet was observed in the bedrock (Franciscan) caused by the Maacama Fault. Similar to the textural cross sections, A-A’ consists primarily of Continental Basin Deposits and low permeability material except for small bands of Quaternary Alluvium around Forsythe Creek and the Russian River. Extent of the Quaternary Alluvium was consistent between the IHCM and textural cross sections. Cross Section B-B’ Cross Section B-B’, Figure 9, runs horizontally across the middle of the UVGB just north of the City of Ukiah in the west to just south of Lake Mendocino in the east, as shown in Figure 5 and Figure 7. The loose sand and gravel of the Quaternary Alluvium is much more present in this region and found on the west side of the cross section near the Russian River. The alluvium was observed across a zone of approximately 10,000 feet wide and varying in thickness from approximately 100 feet to tens of feet thick. This material is likely connected hydraulically to the Russian River due to its proximity. The Maacama fault is located on the eastern edge of the loose alluvium. Directly adjacent to the Quaternary Alluvium are clay and gravel clay layers typically indicative of the Continental Basin Deposits. The clay layers likely separate the coarse alluvium and surface water from the underlying aquifer material and constrain groundwater flow. The lightly to moderately cemented gravels and sand indicative of Terrace Deposits are found in the highlands at the eastern portion of the cross section and above the local water table. Most of the cross section is dominated by clays and gravelly and sandy clays of the Continental Basin Deposits. There is some evidence of buried stream channels at depth with moderately cemented sands and gravels. Due to the larger portion of Quaternary Alluvium found in B-B’, there is an expected greater amount of available groundwater and yield in this portion of the basin. While found in a larger band, the Quaternary alluvium is still constrained to a relatively shallow and narrow portion of the basin. As much of the basin is Continental Basin Deposits, there is an expected significant decrease in groundwater flow and gradient with depth and distance away from the rivers. Some recharge from the overlying Terrace Deposits may occur. The IHCM cross section B-B’ (Appendix A) shows the deepest bedrock (Franciscan) contact at an elevation of approximately -700 feet msl at the center of the cross section. Vertical offset, caused by the Maacama fault, of the basement rock of approximately 100 feet was observed. Similar to the textural cross section, the IHCM B-B’ shows predominantly Continental Basin Deposits with Quaternary Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 16 DRAFT Alluvium found west of the Maacama fault around the Russian River. Extent of the Quaternary Alluvium was consistent between the two cross sections. Cross Section C-C’ Cross section C-C’, Figure 10, is the southernmost cross section in the UVGB, as shown in Figure 5 and Figure 7. Loose sand and gravel of the Quaternary Alluvium is greatest in C-C’ than any of the other sections. It is found at the westernmost end of the cross section and encompasses a nearly 10,000- foot width, similar to that of B-B’, but substantially thicker at approximately 200 feet thick. The Russian River lies in the middle of this western section of alluvium. A smaller portion of loose alluvium is observed on the easternmost boundary of the cross section, just east of the Maacama fault. It is much thinner and occupies a width of approximately 3,000 feet and is observed at a maximum depth of approximately 200 feet thick. These materials are considered to be hydraulically connected with surface water. Surrounding the loose alluvium is the clays and gravely and sandy clays indicative of the Continental Basin Deposits. These extend from below the loose alluvium down to the bedrock contact. There was no evidence of Terrace Deposits in this section. Quaternary Alluvium is occupying the largest area in C-C’ and greater flow and groundwater availability is expected in this portion of the basin. Looser material and greater groundwater flow is expected in the west with limited flow and recharge in the east. At depth, groundwater gradient and flow are reduced due to the high clay content. The IHCM cross section C-C’ (Appendix A) shows the deepest bedrock (Franciscan) contact at -400 feet msl. A vertical offset in the bedrock caused by the Maacama fault of approximately 100 feet was observed. The IHCM cross section shows a deep and wide section of loose alluvium in the west and a narrower section of alluvium just east of the Maacama fault. The majority of the IHCM cross section shows Continental Basin Deposits material. Extent of the Quaternary Alluvium was consistent between the IHCM and textural cross sections. Regional Trends The following regional trends are observed moving north to south from A-A’ to C-C’. 1. Depth to bedrock (Franciscan Formation) decreases from north to south 2. Extent of the loose alluvium (Quaternary Alluvium) increases from north to south. Table 3 shows the characteristics of the Quaternary Alluvium and Franciscan Formation for each cross section. Moving south, the UVGB becomes shallower with the deepest elevation of bedrock contact decreasing from -1,200 feet msl in A-A’ to -400 feet msl in C-C’. The slope of the UVGB floor and walls decreases from A-A’ to C-C’. There is also a general increase in extent and depth of the Quaternary Alluvium in the south. It occupies a narrow extent of 3,000 to 4,000 feet and depths of approximately 20 feet in the north at A-A’. Moving south, there is a significant increase in depth and area of Quaternary Alluvium in B-B’. There is a less significant change between B-B’ and C-C’ with the Quaternary Alluvium occupying the same extent, but at C-C’ occupying greater depths of approximately 200 feet. Regionally, we see a shallowing of the UVGB and an increase in Quaternary Alluvium from north to south. This trend more prominent between A-A’ and B-B’. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 17 DRAFT Table 3: Regional Cross Section Characteristics Franciscan Formation Cross Section Maximum Depth (feet) Maximum Thickness (feet) Maximum Depth (feet mean sea level) A-A'~20 ~3,000-4,000 -1,300 B-B'~100 ~10,000 -700 C-C'~200 ~10,000 -400 Quaternary Alluvium Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 18 DRAFT 5. Principal Aquifers and Aquitards Three principal aquifers make up the UVGB. These aquifers, and their general properties, are: • Principal Aquifer I – Quaternary Alluvium: The primary production aquifer for the UVGB. It is constrained to small, narrow bands along the Russian River and its tributaries. Its extent and depth increases moving south in the basin. • Principal Aquifer II – Terrace Deposits: Thin and discontinuous with low hydraulic conductivities. It is not a major producer of groundwater and may be locally confined. • Principal Aquifer III – Continental Basin Deposits: The thickest of the principal aquifers. It is composed of gravelly/sandy clays interbedded with thick clay and silt layers. It shows low conductivities and groundwater flow is mostly under confined conditions. The aquifer extends from below Principal Aquifer I and II to the Franciscan Formation. All three aquifers are likely hydrologically connected but vary greatly in texture, extent, and hydrogeologic properties. While the Franciscan formation does contain water available in fractures, and small domestic wells are drilled into the formation, they are low yield and the Franciscan is not a significant water bearing formation. For this reason, it is not considered a principal aquifer. Table 4 shows a summary of each aquifer’s extent and conductivities based on both a literature review and pump tests/textural analysis done as part of this HCM. Table 4: Aquifer Characteristics General water quality is good for all three principal aquifers. Aquifer specific water quality is discussed in Section 5.1 through Section 5.3. On a regional scale, water quality data from the GeoTracker program was used to analyze regions of potential water quality concerns in the basin and inform future water quality monitoring networks. GeoTracker is a database system ran by the State Water Resources Control Board (SWRCB) to monitor wells with water quality concerns related to unauthorized releases, leaking underground storage tank (LUST) sites, and other cleanup and non-cleanup sites. Known open GeoTracker sites were plotted and categorized by site type. GeoTracker sites are shown in Figure 11. There is a total of 31 open GeoTracker sites in the UVGB. These sites were characterized as either a cleanup program, LUST site, or a land disposal site. Most of the sites are located near the City of Ukiah. Almost all sites are in a City or along Highway 101 with the exception of three land disposal sites on the fringes of the basin. Hydraulic Properties Thickness Hydraulic Properties Thickness Hydraulic Properties Thickness Cardwell Specific Capacity: 5-400 gpm/ft Yield: > 100 gpm 50-80 ft. Specific Capacity: < 1gpm/ft Yield: App. 60 gpm Up to 200 ft. Specific Capacity: < 1gpm/ft Yield: 50 gpm 1,500 DWR 118 Specific Yield: 20%50-80 ft. Unconfined/confined conditions Up to 200 ft. Up to 2,000 ft. Ferrar Connection to River Yield: up to 1,000 gpm < 100 ft. Specific Capacity: 0.02 - 7.1 gpm/ft Yield: 1-100 gpm Specific Capacity: 0.004 - 1.33 gpm/ft Yield: 0.75-50 gpm Up to 2,000 ft. Specific Capacity: 8-33 gpm/ft Conductivity: 153-218 ft/day 20-200 ft. Specific Capacity:0.1-5.7 gpm/ft Conductivity: 0.23 - 15.75 ft/day Up to 200 ft. Specific Capacity: 0.02-1.95 Conductivity: 0.01-0.51 ft/day > 2,000 ft. Notes: ft. = feet gpm = gallons per minute HCM Recent Alluvium Terrace Deposits Continental Deposits L i t e r a t u r e R e v i e w Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 19 DRAFT Regional water surface elevations are shown on the cross sections, Figure 8 through Figure 10, and were generated based on contours using spring 2019 CASGEM water level data. These contours are discussed in more detail in Section 6. Water surface elevations are near ground surface across the basin for all cross sections with greatest depths to water at the edges of the basin and around 60 feet below ground surface. General water levels in the basin range from a few feet to 20 feet below ground surface in the plains and 60 feet or more in the uplands (Cardwell, 1965). Recharge from precipitation and loss from streams fully replenish the groundwater basin each year (Cardwell, 1965). The following sections provide a more detailed description of the three principal aquifers in the basin including their hydrogeologic characteristics, water quality, and beneficial uses. 5.1 Aquifer I – Quaternary Alluvium Principal Aquifer I – Quaternary Alluvium is composed of highly permeable loose sands and gravels of the Quaternary Alluvium. It is the primary production aquifer of the UVGB. The extent of Aquifer I is shown on both the surficial geology map, Figure 5, and on the cross sections, Figure 8 through Figure 10. While the primary production aquifer, the Quaternary Alluvium occupies a proportionally small area of the basin and is constrained to small bands along the river channels. As discussed in section 4.4.2, depth and thickness of Aquifer I increases moving north to south in the basin. Aquifer I is unconfined with high conductivities that decrease moving away from the stream channels into older deposits (Farrar, 1986). It overlies or is adjacent to both the Terrace Deposits and Continental Basin Deposits of Aquifer II and Aquifer III, respectively. The Quaternary Alluvium is distinguished from the Terrace Deposits by a lack of cementation and clay. It is generally separated from the Continental Basin Deposits by a thick clay layer. Estimated storage capacity of Aquifer I varies between 60,000 to 12,000 acre feet using specific yields between 6 to 10 percent (Farrar, 1986). Due to its proximity to the river systems and high permeability, the Quaternary Alluvium is considered hydraulically connected with adjacent rivers (Cardwell, 1965). Groundwater elevations fluctuate seasonally, and the aquifer generally recharges each year, with the exception of drought conditions (Kunzler Terrace Mine, 2009). Water surface elevations generated for spring 2019 appear near ground surface where Aquifer I was observed (Figure 8 through Figure 10). Hydrogeologic properties for Aquifer I were estimated using available pumping data shown in Table 4. However, the pump test data set for the basin is limited to small-scale tests conducted during construction of the well. This data is less than ideal due to the limited duration of pumping and lack of an observation well. It does however, provide a starting point for estimating hydrogeologic properties of the aquifer and a point of comparison between principal aquifers. A total of six wells with pump test data, accurate locational data, and evidence of being screened in Principal Aquifer I were found. Pumping data was collected from WCR logs. Specific capacity varied between 8 to 75 gpm per foot. Hydraulic conductivity values fluctuated between approximately 150 ft/day and 200 ft/day. This is consistent with expected conductivity values for gravels and coarse sands. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 20 DRAFT Table 5: Principal Aquifer I - Pump Test Data Due to the limited pump test data set, conductivity values were also estimated based on dominant soil texture of the aquifer and average textural conductivity values. In addition to the values listed in Table 5¸conductivity values were estimated from Basic Ground-Water Hydrology (USGS,1983) and are shown in Figure 12. For primarily gravels and coarse sands, expected conductivity values range from in the tens to hundreds of feet per day. Based on observed pump test results and expected values, it is reasonable to assume conductivities to be between 150 to 200 ft/day with increased values in the coarser material near the river channels and decreased values as one moves away from the river and weathering increases. These textbook estimates agree with the values listed in Table 5. 5.2 Aquifer II – Terrace Deposits Aquifer II – Terrace Deposits are composed primarily of moderately cemented sands and gravels with some silts and clays. In the highlands of the basin, the Terrace Deposits occur in thin lenses and are not considered water bearing formations. However, in the valley they can yield moderate amounts of water. Storage capacity for Aquifer II is unknown. Extent of the Terrace Deposits are shown on the surficial geology map, Figure 5, and on the cross sections, Figure 8 through Figure 10. The Terrace Deposits are discontinuous and difficult to discern from the Continental Basin Deposits. Little evidence of Terrace Deposits was observed in well logs in the southern portion of the basin, speaking to the discontinuity of this aquifer. In some areas, the Terrace Deposits occur above the water table and are likely non-water bearing. Aquifer II varies from unconfined to confined based on the amount of clay present. It overlies the Continental Basin Deposits of Aquifer III and either underlies or is adjacent to the Quaternary Alluvium of Aquifer I. Aquifer II is distinguished from Aquifer III based on the amount of clay present as Aquifer III has a significantly more clay than Aquifer II. While not geologically separated from Aquifer I, Aquifer II has significantly lower conductivities and yields than Aquifer I. Hydrogeologic properties for Aquifer II were estimated based on pump test data from WCR logs. A total of 13 wells were identified with pump test data, accurate location data, and evidence of being screened in Aquifer II. Specific capacity values ranged from 0.1 to 8.0 gpm/ft. Hydraulic conductivity values ranged from approximately 0.1 to 15 feet per day. Table 7 shows the WCR pump test data. Log Number Township Range Section Yield (gpm) Drawdown (ft) Specific Capacity (gpm/ft) Transmissivity (ft2/day) Hydraulic Conductivity (ft/day) Screened Interval 215713 15N/12W-NN 20 2 10 2700 180 14-27 156501 -1080 32 34 9113 182 - 61330 15N/12W-28 650 0 ---- 18824 15N/12W-33 75 1 75 20250 153 18-58 34433 15N/12W-28 70 8 9 13125 219 24-76 E0151151 14N/12W-25 300 10 30 8100 135 20-80 Range 9 - 34 2700 - 20250 153 - 218 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 21 DRAFT Table 6: Principal Aquifer II - Pump Test Data Similar to Aquifer I, in addition to results in Table 7, conductivity values were also estimated using dominant soil texture classes of the aquifer and their expected conductivity values (USGS, 1983). Conductivity values for fine sands to silty sands, comparable to the lightly to moderately cemented sands and gravels found in the Terrace Deposits, are estimated between 0.1 and 10 feet per day based on the level of weathering and cementation. These textbook estimates agree with the values in Table 7. 5.3 Aquifer III – Continental Basin Deposits Aquifer III – Continental Basin Deposits is composed primarily of thick clay layers interbedded with gravelly/ sandy clay mixtures. Extent of Aquifer III can be seen on the surficial geology map, Figure 5, and on cross sections, Figure 8 through Figure 10. Aquifer III underlies both Aquifer I and Aquifer II and is distinguished by significant amounts of clay. Aquifer III occupies the majority of the subsurface of the UVGB and is generally in contact with the Franciscan bedrock. Aquifer III has low conductivity and generally low well yields from pockets of buried gravels, sands, or gravelly clays that are separated by thick clay layers (MCWA, 2010). The thick clay layers limit infiltration into the aquifer and reduce recharge. However, the aquifer is generally recharged at the basin margins through infiltration of storm and surface water in addition to deep percolation of irrigation water return flows. Secondary recharge occurs from the fractures in the underlying Franciscan bedrock (Fisher et al., 1965). Storage capacity is estimated at 324,000 acre-feet but difficult to develop due to low permeability (Farrar, 1986). For wells to achieve significant production from Aquifer III, they generally must be deeper wells with longer screen intervals. Hydrogeologic properties for Aquifer III were estimated using available pumping data from the WCRs shown in Table 8. A total of 22 wells were identified with pump test data, accurate locations, and evidence of being screened in Principal Aquifer III. Specific capacity varied between 0.02 to approximately 2.00 gpm per foot. Hydraulic conductivity values varied between approximately 0.01 to Log Number Township Range Section Yield (gpm) Drawdown (ft) Specific Capacity (gpm/ft) Transmissivity (ft2/day) Hydraulic Conductivity (ft/day) Screened Interval 211109 14N/12W-10 20 75 0.3 72 -- E0097559 15N/12W-21 20 50 0.4 108 3 22-60 451246 14N/12W-5 30 167 0.2 270 5 - 118658 14N/12W-14 56 330 0.2 46 0.5 50-150 141377 16N/12W-4 7.5 72 0.1 28 0.2 22-42, 62-82 211546 16N/12W-4 51 50 1 275 3 60-100 125320 16N/12W-3 5 4 1 338 4 58-78 769737 15N/12W-7 4 45 0.1 24 0.1 24-44, 99-159 141431 15N/12W-8 30 38 0.8 213 11 37-57 18817 15N/12W-26 4.5 60 0.1 113 2 41-101 211028 15N/12W-26 40 7 6 1,543 10 20-40 509528 15N/12W-21 50 80 0.6 945 16 29-89 264526 15N/12W-34 40 5 8 2,160 3 45-105 Range 0.1 - 8 24 - 2160 0.2 - 16 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 22 DRAFT 0.51 feet per day. While high for clays, this is consistent with expected conductivity values for gravelly and sandy clays in which wells for Aquifer III are screened in. Table 7: Principal Aquifer III - Pump Test Data Hydrogeologic properties were also estimated using the dominant texture class of the aquifer and expected conductivity values for that texture class, similar to Aquifers I and II. Aquifer III is composed primarily of clays and gravely, sandy clays. For this type of material, expected conductivity values range from the high end of clay material to the low end of silt material with values from 0.001 to 0.1 feet per day. Pump test results skew to the high end of this range which is likely due to the wells being screened in the more permeable material of gravelly and sandy clays. 5.4 Aquifer Water Quality As part of this HCM, water quality as it pertains to the principal aquifers is discussed based on the findings of the literature review. Water quality for the basin will be expanded upon as part of the Basin Setting portion of the GSP and as additional data is available through future monitoring. Aquifer I, the primary production aquifer for the basin, is generally of moderately hard to hard bicarbonate type water (Cardwell, 1965). Dominant groundwater quality constituents are estimated at 40 percent calcium, 40 percent magnesium, and 20 percent sodium (Cardwell, 1965). Locally, water type tends to calcium- bicarbonate in the southern portion of the basin and magnesium-bicarbonate in the east and central portions (Kunzler Terrace Mines, 2009). Chemical signatures for Aquifer I are similar to that of the Russian River, but with higher dissolved solids and chloride levels (DWR, 2004). Log Number Township Range Section Yield (gpm) Drawdown (ft) Specific Capacity (gpm/ft) Transmissivity (ft2/day) Hydraulic Conductivity (ft/day)Screened Interval 775095 16N/12W-28 12 280 0.0 12 0.03 260-280, 340-360, 400-440 705654 16N/12W-22 15 20 0.8 203 0.39 335-415 E0160418 16N/12W-17 7 230 0.0 8 0.01 199-239 705663 15N/12W-NN 2 130 0.0 4 0.01 100-160 E070302 16N/12W-16 15 340 0.0 12 0.01 200-355 705657 15N/12W-35 8 120 0.1 4 0.01 80-100, 220-260 775102 16N/12W-16 8 170 0.1 13 0.01 137-217, 239-257 931929 17N/12W29 15 160 0.1 25 0.05 140-180 18729 17N/12W-32 8 9 0.9 240 0.51 80-150 210815 16N/12W-20 2 90 0.0 6 0.01 186-286 e0255737 17N/12W-29 15 210 0.1 19 0.13 60-220 210813 16N/12W-20 8 220 0.0 10 0.01 278-338 156544 16N/12W-4 6 120 0.1 --83-123 713846 16N/12W-20 13 320 0.0 11 0.01 260-280, 300-360, 380-400 141122 16N/12W-7 30 62 0.5 --40-80 18702 16N/12W-16 215 110 2.0 53 0.42 148-400 E0108596 16N/12W-28 7 200 0.0 10 0.01 120-220 18819 14N/12W-3 40 27 1.5 2,962 -44-104 E0124475 15N/12W-34 20 200 0.1 24 0.05 120-240 e0209535 15N/12W-9 90 200 0.5 122 0.11 150-210 3003 16N/12W-7 7 135 0.1 14 0.03 146-206 398391 16N/12W-8 20 200 0.1 27 0.05 200-340 Range 0.02 - 2 4 - 240 0.01 - 0.51 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 23 DRAFT Due to the connection between Principal Aquifer I and the Russian River, water quality varies seasonally and is greatly affected by surface water conditions. During the baseflow season in late spring and early fall, releases from Lake Mendocino greatly influence the water quality of Aquifer I with respect to specific conductance, total nitrate, and turbidity. In the winter, stormwater flows entering the Russian River increase turbidity and surface runoff pollutants and in turn Principal Aquifer I (Kunzler Terrace Mine, 2009). Total dissolved solids for Aquifer I range from 87 to 301 milligrams per liter with an average of 166 milligrams per liter (DWR, 2004). Table 6 shows general water quality for Aquifer I. General water quality for both the Russian River and Aquifer I are limited and a potential data gap. Additional water quality monitoring would serve to further characterize water type and interaction of the two water sources. Table 8: Principal Aquifer I - Water Quality Principal Aquifer II and Principal Aquifer III have a much more limited water quality data set. As these aquifers are lower producers, wells drilled are mostly private wells which limits the availability of public water quality data. However, there is water quality data from previous studies within the UVGB that help to characterize these aquifers. Water quality in Principal Aquifer II is similar to Principal Aquifer I and of calcium bicarbonate type with a higher concentration of sodium. Lack of hydraulic connection to surface water reduces seasonal fluctuations. Total dissolved solids concentrations are greater in Principal Aquifer II than Principal Aquifer I. Water type is bicarbonate with a higher concentration of sodium. Principal Aquifer III is generally of good water quality but has historical instances of water quality concerns (Fisher et al. 1965). Elevated levels of total dissolved solids have been observed as well as elevated gasses (Fisher et al. 1965, Cardwell, 1965). Wells on the west side of Redwood valley have been observed with explosive levels of flammable gas and pressurized carbon dioxide gas has been encountered during drilling near Coyote Valley, southwest Ukiah, and Talmage (Cardwell, 1965). As Principal Aquifer III may have regions of poor water quality, sampling of wells drilled in this aquifer would help to further define potential areas of concern for future monitoring efforts and address a data gap. 5.5 Aquitards No evidence of significant aquitards within the UVGB were found. However, the significant clay composition of the Continental Basin Deposits influences the flow of groundwater through the system. Groundwater in this layer is generally under confined conditions due to extensive overlying silt and clay layers. This local confinement has been verified by observed rises in water levels for wells drilled into Constituent Parameter Reported range (units as shown)Reference Total Dissolved Solids · Range: 87-301 mg/L · Average: 166 mg/L · 190.0 mg/l (KP-MW 1, 1 July 2005) · 190.0 mg/L (Well P 6 2, October 2002 DWR, 2004; Kunzler Terrace Mine, 2009 Total Hardness · Moderately Hard to Hard Bicarbonate DWR, 2004; Kunzler Terrace Mine, 2009 · 250.0 (July, 2005) · 293.0 (015N012W08F001M3) Electrical Conductivity Kunzler Terrace Mine, 2009 Chloride · 7.3 mg/L (KP-MW 1, 1 July 2005) · 6.1 mg/L (Well P6, 2 October 2002) · 6.5 mg/L (015N012W08F001M3, October 1981) Kunzler Terrace Mine, 2009 Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 24 DRAFT the Continental Basin Deposits (Cardwell, 1965). Where Continental Basin Deposits are found above the water table, perched water may be observed. These clay and silt layers are not extensive enough to truly act as an aquitard and restrict movement between principal aquifers. 5.6 Beneficial Users According to the DWR pursuant to Water Code Sections 10723.8(a)(4) and 10723.2, beneficial uses and users of groundwater in the UVGB to include: • Agricultural • Domestic well owners • Municipal well operators • Public water systems • Land use planning • Resource management • State agencies and other government agencies • California Native American tribes • Private water companies • Disadvantaged communities The primary uses of water are irrigation, domestic, and municipal use. Principal Aquifer I is the main source of groundwater and is used for all these purposes. Principal Aquifer II and Principal Aquifer III are primarily used for domestic water supply due to their limited water supply capabilities. Table 9 shows primary groundwater use by principal aquifer. Table 9: Primary Groundwater Use by Principal Aquifer In 2008 it was estimated that agricultural water consumption in the UVGB was 8,000 acre-feet per year, with 2,500 to 5,500 acre-feet per year from groundwater resources (D.J. Lewis et al., 2008). According to the DWR pursuant to Water Code Sections 10723.8(a)(4) and 10723.2, the agency identifies the major agricultural users in the UVGB to include the Mendocino County Farm Bureau, the Mendocino County Wine Growers Association, and landowners. Agricultural commodities in the UVGB include fruits and nuts, livestock production, poultry products, nursery production, and field crops with the major commodities being wine grapes, timber, pears, apples, and pasture and range (County of Mendocino, 2016). Outside of agriculture, groundwater is used for industrial purposes along with public and domestic supply. Industrial use of groundwater is primarily for sawmills and wood product manufacturing plants. Most of the groundwater used for industry is returned to the Russian River (Cardwell, 1965). Public and Principal Aquifer Do m e s t i c Ag r i c u l t u r e M u n i c i p a l / P u b l i c A g e n c y I n d u s t r i a l Di s a d v a n t a g e d Co m m u n i t i e s Ot h e r I - Quaternary Alluvium X X X X x X II - Terrace Deposits X III - Continental Deposits X Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 25 DRAFT domestic water supply is primarily sourced from groundwater (Cardwell, 1965), with the City of Ukiah as the primary municipal well operator according to DWR pursuant to Water Code Sections 10723.8(a)(4) and 10723.2. There are seven public water systems within the UVGB: Redwood Valley County Water District, Millview County Water District, Willow County Water District, Calpella County Water District, Sonoma County Water Agency, Russian River Flood Control, and Upper Russian River Water Agency. Private water companies include City of 10,000 Buddhas, Rogina Water Company, and Yokayo Water Systems. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 26 DRAFT 6. Groundwater Recharge and Flow Major recharge to Principal Aquifer I is understood to come from the Russian River and its tributaries. This water recharges the loose sands and gravels of Principal Aquifer I but is generally confined to the extent of the aquifer. However, understanding where potential recharge opportunities are throughout the entire basin, along with groundwater flow through the basin, is important to sustainable management under SGMA. To further understand the mechanics of the UVGB groundwater system, general groundwater flow was analyzed along with potential areas of additional recharge and groundwater discharge by: • Spatially plotting areas where soils with potential for infiltration are present • Generating groundwater contours to evaluate groundwater flow throughout the basin Soils with potentially high infiltration were identified based on the hydrologic soil groups presented in Figure 2 and discussed in Section 3.1. Soils that fell into Hydrologic Group A were considered high infiltration soils and regions of potential recharge. Groundwater contours were used to assess general groundwater flow direction and identify regions of potential groundwater discharge. Groundwater contours were developed using water surface elevations from CASGEM wells within the basin. Spring 2019 measurements were used to provide a look at the most recent conditions. Figure 13 shows identified recharge areas along with the spring 2019 water surface elevation contours and the CASGEM wells used to generate them. Historic water surface elevations were analyzed as well to identify any trends in groundwater level fluctuations prior to 2019. Hydrographs have been generated for key CASGEM wells located in the north, central, and southern portion of the basin. These hydrographs, and the CASGEM wells used to generate them, are shown in Figure 14 through Figure 17. Hydrographs present historical fall (October) and spring (April) measurements dating back to 2014. There is very little fluctuation in groundwater levels for the north and central portion of the basin, with seasonal fluctuations ranging to around ten feet but holding steady over the entire study period. There is more fluctuation in the southern portion of the basin, with seasonal fluctuations of nearly 20 feet, but levels remained steady over the study period. In general, between 2014 and 2019, water levels in the basin have remained stable and are similar to those observed in 2019. 6.1 Groundwater Flow Direction and Gradient Water surface elevation contours (Figure 13) show a general flow direction in the basin of north to south with larger flow gradients found in the north and along the edges of the basin. A maximum water surface elevation of 789 feet msl was observed in the northernmost portion of the basin and a minimum elevation of 541 feet msl was observed in the southernmost portion of the basin. Just north of Lake Mendocino, there is a steepening of the groundwater gradient and potential flow away from the Russian River. This may be caused by pumping in the nearby northern cities of the basin. South of the City of Calpella, there is a flattening of the groundwater gradient with flows towards the south and center of the basin. Moving south of Lake Mendocino, groundwater flows in a southwest direction from the uplands and towards the City of Ukiah. A localized groundwater depression is observed near the City of Ukiah which is indicative of groundwater pumping in the region. South of the City of Ukiah, groundwater flow continues at a southwest trend. This provides evidence of a potential wellfield south Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 27 DRAFT of Highway 222 that may be controlling the groundwater gradient. Groundwater surface elevations, following topographic trends, are lowest in the southern portion of the basin, indicating general flow of groundwater to the south. Results of the water surface elevation contours agree with those of previous studies which indicate a general flow direction down valley (north to south) and towards the Russian River, with gradients lowest in the alluvium of the basin and highest in the less permeable material of the uplands (Cardwell, 1965). Vertical flow within the aquifer system is not well understood and is a potential data gap that may be filled through the construction of multi-level monitoring wells. 6.2 Recharge Areas However, as discussed earlier, historical studies indicate that much of the basin is recharged through precipitation with shallow alluvial aquifers receiving recharge through stream losses and deeper recharge through deep percolation on the edges of the basin and through fractures in the Franciscan bedrock (Cardwell, 1965). Recharge along the edges of the basin contributes to the Continental Basin Deposits and is likely slow percolation of precipitation or stormwater (Cardwell, 1965). Through analyzing where regions of Hydrologic Soil Group A are found within the basin, a more complete picture of areas recharge in the basin was developed. Soils falling in Group A were chosen due to their high saturated infiltration potential. These soil zones, shown in Figure 11, are located primarily in small bands around the Russian River and its tributaries. Small pockets of high infiltration soils are observed away from the river channels. These may be evidence of historical river channels or alluvial material that is less weathered. The extent of the potential recharge areas identified in Figure 11 coincide with findings from the literature and illustrated in the developed textural cross sections. The majority of significant recharge within the basin occurs where coarse to slightly weathered alluvium of Principal Aquifer I is found either at current river channels or historic channels. Moving away from the river there are pockets of lightly weathered material may contribute to recharge but where the Terrace Deposits and Continental Basin Deposits of Principal Aquifer II and Principal Aquifer III outcrop, infiltration drops significantly. The likely reason for stabilization of water levels in these two aquifers is the lack of significant extraction in either. 6.3 Discharge Areas Discharge areas within the basin were determined by analyzing the groundwater contours and flow directions illustrated in Figure 11. The groundwater depression located around the City of Ukiah shows extraction of groundwater through a local wellfield. This depression is the most significant feature in the UVGB and is likely the greatest source of groundwater discharge in the basin. The continuation of a southwest trend in groundwater flow south of Highway 222, and a generally low groundwater levels, provides evidence of a potential well field south of the highway controlling groundwater flow. Groundwater may flow back into the Russian River to discharge at the southern end of the basin, but with little groundwater data in the area it is uncertain at this time. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 28 DRAFT 7. Surface Water The two major surface water features within the UVGB include Lake Mendocino along with the Russian River and its tributaries. Lake Mendocino is located on the eastern edge of the UVGB, just southeast of Calpella. Lake Mendocino is a federal water supply and flood control reservoir managed by Sonoma Water. Sonoma Water is a wholesale water supply and manages water supply storage and releases to maintain minimum instream flows in the Russian River and to meet water supply demands for both Sonoma Water and Russian River water users (Sonoma County Water Agency, 2016). It was constructed in 1944 for flood control, water supply, recreation, and streamflow regulation. Flood control operations for Lake Mendocino are controlled by the USACE. The Russian River runs north to south through the center of the UVGB. It enters the basin at the northernmost end and exits at the southernmost end, just north of Hopland. Significant controls on surface water flows in the Russian River are releases from Lake Mendocino. Headwaters of the Russian River is located 15 miles north of Ukiah. It is habitat to endangered salmonid species and subject to minimum flow requirements established under the Federal Endangered species Act (ESA) (Sonoma Water, 2016). 7.1 Surface Water Characterization The Russian River is the main flowing water body within the UVGB. It extends for the entire length of the basin from north to south for approximately 33 miles with several tributaries connecting to it (LACO, 2017). Most of the contributing tributaries are seasonal or intermittent, as shown in Table 10. However, many of the intermittent streams have been shown to be flowing upstream and within the basin area while disconnected from the Russian River. A recent local study by the Ukiah farming community during the 2018 water year has provided observational insights into the flowing patterns of the major tributaries to the Russian River within the UVGB (Robinson, 2019). It is worth noting that the available information provided through this study (summarized in Table 10) corresponds to a relatively dry year and cannot necessarily be representative of all weather conditions. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 29 DRAFT Table 10: Russian River Tributaries within the UVGB and Flow Periods Tributary Name Description Approximate Drainage Area (mi2) Flowing period during 2018 Water Year Sulphur Creek (Vichy Creek) An eastern tributary with only a small portion located within the UVGB. 7.5 Flows into the basin and the Russian River from November through June McClure and Mill Creek Both eastern tributaries. Drain from Cow Mountain and join to discharge into the Russian River just north of the Talmage bridge. 18 Perennial flow, but December to April discharge to the Russian River Howel Creek An eastern tributary, it enters the basin under multiple branches. It has noncontiguous pools when it is dry. 10 Wet season flow only. Drains to the Russian River only during and after strong rainfall. Morrison Creek An eastern tributary, flows perennially in the upstream and mountainous streambed. Can become subsurface passing the alluvial streambeds. 10 Flows into the basin and the Russian River from December through March Forsyth Creek A western tributary, it drains the largest area to the basin. 28 Almost year round flow, disconnects from the Russian River in June (late Spring) York Creek A western tributary, it drains into the Russian River north of the East and West Fork confluence. It has one NMFS streamflow gauge. 14 Perennial flow. Disconnected from the Russian River in June. Hensley Creek A western tributary with a relatively small watershed. 7.5 Flows into the basin and the Russian River from the start of the wet season through June Ackerman Creek A western tributary that shows occasional significant flows. In the spring wet stretches of creek bed can be seen downstream of dry stretches, showing significant interactions of stream with subsurface flow. 20 Disconnects from the Russian River in June Orrs Creek A western tributary that flows through the urban (City of Ukiah) and agricultural landscapes. 20 Flows through late Summer but disconnects from the Russian River in May. Gibson and Doolan Creeks A western tributary, it enters the basin in three separate branches. It includes segments of artificial channels and culverts and drains into the Russian River immediately north of the Talmage Bridge. 8 Flows through late Summer but disconnects from the Russian River in May. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 30 DRAFT Robinson Creek A western tributary with a sizeable watershed that can show significant flows in winter. It becomes subsurface flow in late spring and summer, while flowing on the long stretch of alluvial downstream bed. It has one NMFS streamflow gauge. 26 Perennial flow, but disconnects from the Russian River in June McNab Creek A western tributary that is gauged at three locations by the CLSI and one location by NMFS. 13 No available information. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 31 DRAFT Streamflow of the Russian River and the contribution of its tributaries is measured at three USGS streamflow gauges, four National Marine Fisheries Service (NMFS) gauges, and three California Land Stewardship Institute (CLSI) gauges, shown in Figure 18. Table 11 presents the location of the USGS stations as well as Station 11462500, which is located on Russian River just downstream of the Ukiah Valley Basin and upstream of the City of Hopland. Stations 11462000 and 11461000 are no longer monitored by the USGS and have been reassigned to the DWR and monitored through the California Data Exchange Center (CDEC) under Site IDs CDM and RRU, respectively. By the time of this report, data from the NFMS and CLSI gauges have not been made available. It is worth noting that major uncertainties and doubts have been expressed by the GSA members and stakeholders within the basin regarding the measurement accuracy of the NMFS gauges in the recent years. As a result, streamflow analysis is limited to the data available from the USGS and CDEC gauges. Table 11: USGS Stations within the Ukiah Valley Basin Station ID Location Long-term Average (cfs) Percent Dry Years Dry Years Average (cfs) Wet Years Average (cfs) 11461000 Russian River North of Ukiah 153 59% 126 232 11462000 East Fork Russian River 273 59% 168 351 11462080 Russian River near Talmage 399 50% 192 518 11462500 Russian River North of Hopland 605 53% 353 759 The following three streamflow gauging stations can provide an overall characterization of the flow within the basin: • Station 11462000: Representative of the East Fork Russian River and releases from the Lake Mendocino. • Station 11461000: Representative of the West Fork Russian River up to north of the City of Ukiah and before the confluence of the East Fork and West Fork. • Station 11462500: Representative of the total flow drained from the basin located downstream of the UVGB. Table 12 presents monthly average of streamflow at each of these stations along with their minimum and maximum historical streamflow. As presented in this table, January through March are the months with the highest flows in all three stations and June through September are the driest months with the lowest flows. However, West Fork Russian River experiences its dry conditions as early as May and remains relatively dry through November. East Fork of Russian River is the main contributor to the river during this dry period. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 32 DRAFT Table 12: Monthly and long-term average, minimum and maximum historical streamflow Month Station 11462500 Russian River North of Hopland (cfs) Station 11462000 East Fork Russian River (cfs) Station 11461000 Russian River North of Ukiah (cfs) January 1563 519 406 February 1517 478 442 March 1118 308 356 April 592 278 168 May 297 229 59 June 176 195 16.2 July 174 222 3.3 August 181 229 0.8 September 179 229 0.6 October 197 224 6.8 November 220 170 40.5 December 920 208 335 Max historical flow 27,403 5,329 10,083 Min historical flow 21 5 0 Figure 19 illustrates the mean annual streamflow at these three USGS stations. Figure 20 through Figure 22 show mean daily streamflow at each individual station. As demonstrated in this figure, 1998 has been the wettest year on record. The most recent wet year has been 2017. The driest year on record at these stations have been 2013. Overall, the last decade has been considerably drier than its preceding decades, which shows the effect of the most recent drought. Water Systems Operations The surface water system of the UVGB is controlled by releases from Lake Mendocino into the Russian River along with precipitation and stormwater runoff. Inflow into Lake Mendocino is approximately 235,000 acre-feet per year, with a peak annual inflow of 443,000-acre feet in 1983 and a minimum annual inflow of 60,000 acre-feet in 1977 (Sonoma County Water Agency, 2016). Storage capacity of the lake is 116,500-acre feet with a water supply pool between 68,400 acre-feet and 111,000 acre-feet (Sonoma County Water Agency, 2016). It is supplied by both the Eel River and PG&E’s Potter Valley Project. During the winter months, flow in the Russian River is mainly unimpaired stream flow supplied through precipitation and runoff. In the summer months, flow is primarily supplied by storage releases from Lake Mendocino (Sonoma County Water Agency, 2016). Under the SWRCB Decision 1610, the Russian River is subject to minimum instream flow requirements. To guide these requirements, hydrologic conditions of Normal, Dry, and Critical were established and based on inflow into Lake Pillsbury of the Porter Valley Project. Hydrologic conditions are based on the following criteria described in acre-feet of storage in Lake Pillsbury (Sonoma County Water Agency, 2016): Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 33 DRAFT Dry • 8,000 acre-feet as of January 1 • 39,200 acre-feet as of February 1 • 65,700 acre-feet as of March 1 • 114,500 acre-feet as of April 1 • 145,600 acre-feet as of May 1 • 160,000 acre-feet as of June 1 Critical • 4,000 acre-feet as of January 1 • 20,000 acre-feet as of February 1 • 45,000 acre-feet as of March 1 • 50,000 acre-feet as of April 1 • 70,000 acre-feet as of May 1 • 75,000 acre-feet as of June 1 Normal hydrologic conditions exist whenever dry or critical conditions aren’t present (Sonoma County Water Agency, 2016). These conditions guide the minimum flow requirements for the upper reach of the Russian River, which constitutes the stretch of the river starting at Lake Mendocino down to south of the UVGB border. Under normal conditions, 185 cfs is required within the river from April 1 through August 1 and 150 cfs from September 1 to March 31. During dry conditions, 75 cfs is required in the river and under critical conditions 25 cfs (Sonoma County Water Agency, 2016). However, under the recommendation of the National Marine Fisheries (NMFS) Russian River Biological Opinion (NMFS, 2008), instream flow requirements were reduced. A permanent reduction to 125 cfs between June 1 and August 31 and from September 1 and October 31 applied to the upper Russian River. Summer releases from Lake Mendocino or controlled based on these criteria with minimum flow thresholds maintained. 7.2 Groundwater – Surface Water Interaction Understanding of the relationship between groundwater and surface water is a key factor in sustainable management of a basin and one of the larger data gaps in this HCM. Based on previous studies, it is understood that Principal Aquifer I is hydraulically connected with the Russian River. What isn’t understood is the magnitude of that connection. As discussed in Section 7.1, there is limited surface water gauge sites and streamflow data available for the basin. In addition, the basin lacks a sufficient monitoring well networks to correlate groundwater level response to stream stage. Efforts are being made to fill in this data gap and the UVGB is currently working with LWA to develop a sufficient monitoring network. The proposed monitoring network is shown in Figure 23. A total of eight monitoring well transects are proposed. Locations are correlated to known surface water gauges in the basin. These are proposed locations and may change based on findings of exploratory borings and further investigation into available surface water data. Key transects are those tied to USGS gauges, as the USGS gauges currently maintained have the highest probability of having accurate flow data. LWA and the UVGB are in the process of securing funding for the exploratory borings and expect drilling to occur in fall/winter 2019. Additionally, monitoring well transects provide opportunity for additional groundwater quality sampling. These samples not only enhance the understanding of aquifer water quality but also the connection between Russian River water and groundwater. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 34 DRAFT 8. Data Gaps During the development of this HCM, and through the IHCM, data gaps were identified to be addressed for sustainable basin management under SGMA. These data gaps include: • Development of a North-South cross section to further enhance the understanding of aquifer and lithologic trends of the UVGB. • Incorporate high resolution USGS gravimetric data to refine the basin bottom where available. • Conducting of long-term pump tests to establish refined hydrogeologic characteristics (conductivity, specific capacity, storativity, specific yield) for principal aquifers • Conduct water quality sampling to further refine the water chemistry of the basin and identify where additional monitoring, if needed, is required. o General chemistry analysis from water quality sample results to characterize Principal Aquifer I and the Russian River o Identify potential areas of water quality concerns for future monitoring • Completion of monitoring well transects to quantify and establish surface water groundwater interaction. • Establishment of working and reliable surface water gauges with which to characterize surface monitor flow • Russian River/Principal Aquifer I Water Quality: Additional sampling to compare and contrast water chemistry of the Russian River and Principal Aquifer I to determine the connection between the two • Construction of multi-level monitoring wells at key locations in the basin to establish vertical flow of groundwater within the basin. • Understanding of imported and exported water supplies within the UVGB. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 35 DRAFT 9. References California Department of Water Resources, 2017. California Groundwater – Legislation, Sustainable Groundwater Management Act California Department of Water Resources, December 2016. Best Management Practices for the sustainable Management of Groundwater – Hydrogeologic Conceptual Model BMP. California Department of Water Resources, January 2006. California’s Groundwater Bulletin 118 Update 2018 Report California Department of Water Resources, February 2004. California’s Groundwater Bulletin 118 – North Coast Hydrologic Region, Ukiah Valley Groundwater Basin California Geological Survey, 2017. Fault Activity Map of California (2010). California Department of Conservation. http://maps.conservation.ca.gov Cardwell , G.T, 1965. Geology and Ground Water in Russian River Valley Areas and in Round, Laytonville, and Little Lake Valleys – Sonoma and Mendocino Counties, California. Geological Survey Water-Supply Paper 1548. In cooperation with the California Department of Water Resources Erickson, G., May 2008. Evolution of an Intermontane Basin Along the Maacama Fault, Little Lake Valley, Northern California. Humboldt State University. Farrar, C.D., July 1986. Groundwater Resources in Mendocino County, California. United States Geological Survey (USGS) Fisher, Brown, and Warne, April 1965. North Coast Hydrographic Area, Volume 1: Southern Portion, Bulleting No. 142-1. Department of Water Resources. Frederiksen, J., 2015. Water District North of Ukiah Can Add Customers. Ukiah Daily Journal. Fuller, M., Brown, S., Wills, C., and Short, W., 2015. Geological Gems of California State Parks, Special Report 230. California Geological Survey under Interagency Agreement C01718011 with California State Parks. ISRP, 2016. Conceptual Model of Watershed Hydrology, Surface Water and Groundwater Interactions and Stream Ecology for the Russian River Watershed. Russian River Independent Science Review Panel. Larsen and Kelsey, April 2005. Geologic Maps of late Neogene and Quaternary Deposits in the Ukiah Basin. Humboldt State University – State of California Department of Water Resources – United States Department of the Interior Geologic Survey. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 36 DRAFT LACO Associates, December 28, 2017. Initial Groundwater Sustainability Plan Hydrogeologic Conceptual Model. Mclaughlin, R. J. et al. 2012. Evolution of the Rodgers Creek-Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California. Geosphere. Geological Society of America. Mendocino County Water Agency (MCWA), October 2010. Water Supply Assessment for the Ukiah Valley Area Plan National Marine Fisheries Service, 2008. Biological Opinion for Water Supply, Flood Control Operations, and Channel Maintenance. U.S. Army Corps of Engineers, Sonoma County Water Agency, and Mendocino County Russian River Flood Control and Water Conservation Improvement District. Natural Resources Conservation Service, 2014. Keys to Soil Taxonomy. United States Department of Agriculture. R. Rexford, 1989. Holocene Activity and Tectonic Setting of the Maacama Fault Zone, Mendocino County. Engineering Geology Volume 27. Issues 1-4, Pages 375-412. Robinson, Z, 2019. Tributary Flow Patterns for the Ukiah Groundwater Basin. Unpublished report and raw data. Sonoma County Water Agency, August 2016. Fish and Habitat Flows and Water Rights Project, Draft Environmental Impact Report. Heath, R. 1983. Basic Ground-Water Hydrology, Water-Supply Paper 2220. U.S. Department of the Interior, U.S. Geological Survey. Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 37 DRAFT Figures Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 38 DRAFT Figure 1: Basin Setting Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 39 DRAFT Figure 2: Hydrologic Soils Groups Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 40 DRAFT Figure 3: Taxonomic Soil Orders Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 41 DRAFT Figure 4: Surficial Geology Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 42 DRAFT Figure 5: Well and Cross Section Locations Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 43 DRAFT Figure 6: Cross Section A-A' with Well Locations Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 44 DRAFT Figure 7: Cross Section B-B' and C-C' with Well Locations Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 45 DRAFT Figure 8: Cross Section A-A' Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 46 DRAFT Figure 9: Cross Section B-B' Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 47 DRAFT Figure 10: Cross Section C-C' Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 48 DRAFT Figure 11: Open GeoTracker Sites Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 49 DRAFT Figure 12: Basic Groundwater Hydrology Paper 2220 - Conductivity Values Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 50 DRAFT Figure 13: Groundwater Recharge and Flow Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 51 DRAFT Figure 14: CASGEM Hydrograph Wells Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 52 DRAFT Figure 15: UVGB North Hydrograph Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 53 DRAFT Figure 16: UVGB Central Hydrograph Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 54 DRAFT Figure 17: UVGB South Hydrograph Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 55 DRAFT Figure 18: Available Streamflow Measurement Gauges within the UVGB Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 56 DRAFT Figure 19: Mean Annual Streamflow at Select Stations Figure 20: Mean Daily Streamflow; Station 11462500 Russian River North of Hopland Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 57 DRAFT Figure 21: Mean Daily Streamflow; Station 11462000 East Fork Russian River Figure 22: Mean Daily Streamflow; Station 11461000 Russian River North of Ukiah Hydrogeologic Conceptual Model GEI Consultants, Inc. Ukiah Valley Basin 58 DRAFT Figure 23: Proposed Groundwater/Surface Water Monitoring Network Appendix A. LACO Initial Hydrogeologic Conceptual Model Initial Groundwater Sustainability Plan Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin Mendocino County, California DWR Grant No. 4600011503 December 28, 2017 Prepared for: Mendocino County Water Agency Prepared By: LACO Associates 311 S. Main Street Ukiah, California 95482 (707) 462-0222 Project No. 7746.09  advancing the quality of life for generations to come Design Planning Engineering Geology and Geotechnical Environmental Science Materials Testing Survey 707 462 0222 www.lacoassoicates.com Eureka _ Ukiah _ Santa Rosa %ULDQ0:DOODFH060%$(,7 6WDII(QJLQHHU, &KULVWRSKHU-:DWW&+* 3ULQFLSDO+\GURJHRORJLVW Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI TABLE OF CONTENTS 1.0 Introduction .......................................................... 5 1.1 Purpose .......................................................... 6 1.2 Geographic Setting .......................................... 6 1.3 Hydrogeologic Conceptual Model Development ..... 6 1.4 Significant Assumptions .................................... 6 2.0 Previous studies and data collection ......................... 6 2.1 Literature Review ............................................ 7 2.2 Ongoing Hydrogeologic Data Collection Programs . 9 2.2.1 Surface Water Data Collection Programs ... 9 2.2.2 Groundwater Monitoring Data Collection Programs ............................................ 10 3.0 Historical Groundwater Elevation Database Development .............................................................. 11 4.0 WCR Database Development ................................... 12 5.0 Groundwater Basin Boundary History ....................... 13 6.0 Geologic Setting .................................................. 14 6.1 Geologic Formations ....................................... 14 6.1.1 Quaternary Alluvium ............................. 14 6.1.2 Terrace Deposits .................................. 14 6.1.3 Continental Basin Deposits ..................... 15 6.1.4 Franciscan Formation ............................ 16 6.2 Maacama Fault .............................................. 16 6.3 Geologic History ........................................... 17 6.4 Geologic Cross Sections .................................. 17 Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI 6.4.1 Distinction of Formation Boundaries ........ 17 6.4.2 Discussion/Interpretation of Geologic Cross Sections ............................................. 18 7.0 Bottom Of Groundwater Basin ................................ 19 8.0 Principal Aquifers and Aquitards ............................ 19 8.1 Aquifer I – Quaternary Alluvium ...................... 19 8.1.1 Aquifer I – Physical Properties .............. 19 8.1.2 Aquifer I – Water Quality ..................... 21 8.1.3 Aquifer I – Primary Uses ....................... 21 8.2 Aquifer II – Continental Basin Deposits ............. 22 8.2.1 Aquifer II – Physical Properties ............. 22 8.2.2 Aquifer II – Water Quality .................... 24 8.2.3 Aquifer II – Primary Use ....................... 24 8.3 Franciscan Formation ...................................... 24 8.3.1 Franciscan Formation – Physical Properties24 8.3.2 Franciscan Formation – Water Quality ..... 25 8.3.3 Franciscan Formation – Primary Use ........ 25 9.0 Future Work ........................................................ 25 10.0 References ......................................................... 26 11.0 List of Acroynms .................................................. 29  Figures )LJXUH 89*%9LFLQLW\DQG86*67RSRJUDSK\0DS )LJXUH*HRORJLF0DS )LJXUH &URVV6HFWLRQ$$· )LJXUH &URVV6HFWLRQ%%· )LJXUH &URVV6HFWLRQ&&· Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI )LJXUH 15&66RLO0DS )LJXUH 5HFKDUJH$UHD0DS )LJXUH 6XUIDFH:DWHU6XSSO\0DS )LJXUH ,PSRUWHG:DWHU0DS Appendix 1  &DUGZHOO8NLDK9DOOH\+\GURJHRORJ\ Appendix 2 ':5%XOOHWLQ Appendix 3 )HUUDU8NLDK9DOOH\+\GURJHRORJ\6WXG\ Appendix 4 89$36WXG\*URXQGZDWHU6XSSOLHV Appendix 5 5XVVLDQ5LYHU,6535HSRUW Appendix 6 89*%+\GURJUDSKV Appendix 7 :HOO&RPSOHWLRQ5HSRUWV   Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI 1.0 INTRODUCTION $+\GURJHRORJLF&RQFHSWXDO0RGHO +&0 IRUWKH8NLDK9DOOH\*URXQGZDWHU%DVLQ 89*% LVSUHVHQWHG 7KH+&0KDVEHHQSUHSDUHGWRPHHWWKHUHTXLUHPHQWVOLVWHGLQWKH(PHUJHQF\6XVWDLQDEOH*URXQGZDWHU 0DQDJHPHQW$FW 6*0$ 5HJXODWLRQV&KDSWHU$UWLFOH6XEDUWLFOH† ':5 )XQGLQJIRU DQ ,QLWLDO *URXQGZDWHU 6XVWDLQDELOLW\ 3ODQ ,*63  ZDV SURYLGHGE\ WKH &DOLIRUQLD 'HSDUWPHQW RI :DWHU 5HVRXUFHV ':5 WRWKH0HQGRFLQR&RXQW\:DWHU $JHQF\ 0&:$ 3HU6*0$WKHUHJXODWLRQVIRUWKH +&0DUHDVIROORZV a) Each Plan shall include a descriptive Hydrogeologic Conceptual Model of the basin based on technical studies and qualified maps that characterizes the physical components and interaction of the surface water and groundwater systems in the basin. b) The Hydrogeologic Conceptual Model shall be summarized in a written description that includes the following: 1) The regional geologic and structural setting of the basin including the immediate surrounding area, as necessary for geologic consistency. 2) Lateral basin boundaries, including major geologic features that significantly affect groundwater flow. 3) The definable bottom of the basin. 4) Principal aquifers and aquitards, including the following information: A) Formation names, if defined. B) Physical properties of aquifers and aquitards, including the vertical and lateral extent, hydraulic conductivity, and storativity, which may be based on existing technical studies or other best available information. C) Structural properties of the basin that restrict groundwater flow within the principal aquifers, including information regarding stratigraphic changes, truncation of units, or other features. D) General water quality of the principal aquifers, which may be based on information derived from existing technical studies or regulatory programs. E) Identification of the primary use or uses of each aquifer, such as domestic, irrigation, or municipal water supply. 5) Identification of data gaps and uncertainty within the Hydrogeologic Conceptual Model. c) The Hydrogeologic Conceptual Model shall be represented graphically by at least two scaled cross sections that display the information required by this section and are sufficient to depict major stratigraphic and structural features in the basin (Figures 3, 4, and 5). d) Physical characteristics of the basin shall be represented on one or more maps that depict the following: 1) Topographic information derived from the U.S. Geological Survey or another reliable source (Figure 1). 2) Surficial geology derived from a qualified map including the locations of cross sections required by this Section (Figure 2). 3) Soil characteristics as described by the appropriate Natural Resources Conservation Service soil survey or other applicable studies (Figure 6). 4) Delineation of existing recharge areas that substantially contribute to the replenishment of the basin, potential recharge areas, and discharge areas, including significant active springs, seeps, and wetlands within or adjacent to the basin (Figure 7). 5) Surface water bodies that are significant to the management of the basin (Figure 8). The source and point of delivery for imported water supplies (Figure 9). 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Maximum Unit Thicknesses of Aquifers in Cross Sections &URVV6HFWLRQ4WXE &RPELQHGNYDOXHV 4WXE .XQNQRZQ /RZ.4WXE+LJK.4WXE4DO $²$·    %²%·    &²&·       &URVVVHFWLRQ$$· )LJXUH KDVDZLGWKRIIHHWDQGDPD[LPXPGHSWKRIIHHWEHORZJURXQG VXUIDFH EJV 7KH0DDFDPD)DXOWLQWHUVHFWVWKHZHVWHUQVLGHRIWKHFURVVVHFWLRQ,QFURVVVHFWLRQ$$·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· )LJXUH KDVDZLGWKIHHWRIDQGDGHSWKRIIHHWEJV7KH0DDFDPD)DXOW UXQVWKURXJKWKHFHQWHURIWKLVFURVVVHFWLRQ&URVVVHFWLRQ%%·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· )LJXUH KDVDZLGWKRIIHHWDQGDGHSWKRIIHHWEJV7KH0DDFDPD)DXOW UXQVWKURXJKWKHHDVWHUQVLGHRIWKHFURVVVHFWLRQ+LJKK\GUDXOLFFRQGXFWLYLW\FRQWLQHQWDOEDVLQGHSRVLWV DUHSUHVHQWWRWKHZHVWRIWKH0DDFDPDIDXOWZLWKDWKLFNQHVVRIDSSUR[LPDWHO\IHHWDQGWRWKHHDVW Hydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI RIWKHIDXOWZLWKDWKLFNQHVVRIDSSUR[LPDWHO\IHHW4XDWHUQDU\ DOOXYLXP LV SUHVHQW DERYH WKH KLJK K\GUDXOLFFRQGXFWLYLW\FRQWLQHQWDOGHSRVLWVDQGLVH[SRVHGWRWKHVXUIDFHQHDUWKH5XVVLDQ5LYHU  7.0 BOTTOM OF GROUNDWATER BASIN 7KHGHSWKWRWKH)UDQFLVFDQIRUPDWLRQYDULHVWKURXJKRXWWKHYDOOH\7KHERWWRPRIWKHJURXQGZDWHUEDVLQ ZDV HVWLPDWHG IURP JUDYLPHWHU GDWD SURYLGHG LQ D +XPEROGW 6WDWH 8QLYHUVLW\ 0DVWHU·V WKHVLV (ULFNVRQ  *UDYLPHWHUVXUYH\GDWDZDVFDOLEUDWHGWRJUDYLW\DQRPDO\GDWDFROOHFWHGIURP:&5V&RQWLQHQWDO EDVLQGHSRVLWILOOZDVHVWLPDWHGWREHLQGHSRVLWLRQDOFRQWDFWZLWKVKDOORZO\GLSSLQJEHGURFNRQWKHHDVW DQGZHVWPDUJLQVRIWKHYDOOH\7KHFURVVVHFWLRQVSURYLGHGLQWKHWKHVLVVWXG\HQGHGDSSUR[LPDWHO\KDOI ZD\DORQJWKHQRUWKVRXWKD[LVRIWKHYDOOH\DQGWKHUHIRUHWKHGHSWKWREHGURFNZDVLQWHUSRODWHGWRWKH VRXWKEDVHGRQGHSWKWREHGURFNGDWDIURP:&5V7KHJUHDWHVWGHSWKVWRWKH)UDQFLVFDQIRUPDWLRQ,Q FURVVVHFWLRQV$²$·%²%·DQG&²&· )LJXUHVDQG DUHDSSUR[LPDWHO\IHHWIHHWDQG IHHWUHVSHFWLYHO\  8.0 PRINCIPAL AQUIFERS AND AQUITARDS 7ZRSULQFLSDODTXLIHUVDUHLGHQWLILHG $TXLIHU,²4XDWHUQDU\DOOXYLXP DQG $TXLIHU,,²FRQWLQHQWDOEDVLQ GHSRVLWV*URXQGZDWHURFFXUVLQWKHIUDFWXUHVRIWKH)UDQFLVFDQIRUPDWLRQKRZHYHULWLVQRWDSULQFLSDO DTXLIHU 7KLV VHFWLRQ GHVFULEHV WKH DTXLIHUV SK\VLFDO SURSHUWLHV +\GUDXOLF FRQGXFWLYLW\ WUDQVPLVVLYLW\ VWRUDWLYLW\VSHFLILF\LHOGDQGZHOO\LHOG ZDWHUTXDOLW\DQGWKHSULPDU\XVHVRIHDFKSULQFLSDODTXLIHU  8.1 Aquifer I – Quaternary Alluvium $TXLIHU,LVWKHSULPDU\K\GURJHRORJLFXQLWIRUJURXQGZDWHUVXSSO\LQWKH89*%7KH4XDWHUQDU\DOOXYLDO GHSRVLWVSURYLGHWKHKLJKHVWZHOO\LHOGVDQGVSHFLILFFDSDFLWLHV6XPPDULHVRIWKHSK\VLFDOSURSHUWLHV VWUXFWXUDO SURSHUWLHV JHQHUDO ZDWHU TXDOLW\ DQG SULPDU\ XVH RI $TXLIHU, DUH GLVFXVVHG LQ WKH IROORZLQJ VHFWLRQV  8.1.1 Aquifer I – Physical Properties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ydrogeologic Conceptual Model Ukiah Valley Groundwater Basin | Initial Groundwater Sustainability Plan Mendocino County Water Agency | DWR Grant No. 4600011503 3URMHFW1R'HFHPEHU 3DJHRI 9DOOH\EXWGLVFRQWLQXRXVO\DORQJIODQNVLQWKH8NLDK9DOOH\ 1&+5 $TXLIHU,K\GURJHRORJLFSURSHUWLHV EDVHGRQWKH:&5'DWDEDVHDUHSURYLGHGLQ7DEOH  Table 4. 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HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE Date: 12/23/2017 Time: 11:39:07 AM UVGB Vicinity and USGS Topography Map BMW CJW - 12/13/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115031 1 Legend Ukiah Valley Groundwater Basin (UVGB) Boundary County Boundaries 02.551.25 Miles Ukiah Valley Groundwater Basin, Mendocino County, California For All Figures: Service Layer Credits: Sources: Esri, HERE, DeLorme, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo, MapmyIndia, © OpenStreetMap contributors, and the GIS User Community USGS The National Map: National Boundaries Dataset, National Elevation Dataset, Geographic Names Information System, National Hydrography Dataset, National Land Cover Database, National Structures Dataset, and National Transportation Dataset; U.S. Census Bureau - TIGER/Line; HERE Road Data LACO EUREKA ● UKIAH ● SANTA ROSA 1-800-515-5054 www.lacoassociates.com NO. HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE Date: 12/27/2017 Time: 6:50:41 AM Geologic Map BMW CJW - 12/13/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115032 1 Legend Groundwater Elevation Measurements Well Completion Reports Cross Sections Faults Continental Basin Deposits (QTub) Franciscan Formation (KJf) Terrace Deposits (Qt) Quaternary Alluvium (Qal) UVGB Boundary 01.530.75 Miles A A' B B' C C' .MI 4WXE 4DO .MI )H H W +LJK. 4WXE )HHW /RZ. 4WXE /RZ. 4WXE +LJK. 4WXE 0DDFDPD )DXOW )RUV\WKH &UHHN +LJK. 4WXE +LJK. 4WXE 5XVVLDQ 5LYHU 4DO 4DO .MI.MI )HHW /RZ. 4WXE 0DDFDPD )DXOW 4WXE 4WXE /RZ. 4WXE+LJK. 4WXE +LJK. 4WXE +LJK. 4WXE 5XVVLDQ5LYHU 4DO .MI 4WXE .MI )HHW 4DO/RZ. 4WXE 4WXE +LJK. 4WXE /RZ. 4WXE +LJK. 4WXE +LJK. 4WXE +LJK. 4WXE 0DDFDPD )DXOW 5XVVLDQ5LYHU LACO EUREKA ● UKIAH ● SANTA ROSA 1-800-515-5054 www.lacoassociates.com NO. HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE Date: 12/23/2017 Time: 11:33:19 AM NRCS Soil Map BMW CJW - 12/13/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115036 1 Legend UVGB Boundary Soil Name Access denied Argixerolls Casabonne Cole Cummiskey Dam Etsel Feliz Gielow Hellman Hopland Kekawaka Montara Pinnobie Pinole Pits Redvine Riverwash Rock outcrop Russian Squawrock Talmage Unnamed Water Witherell Wohly Woodin Yokayo Yorktree Yorkville 01.530.75 Miles Soil data was obtained from the NRCS Web Soil Survey (NRCS, 2017, Web Soil Survey, United States Department of Agriculture, Natural Resources Conservation Service). LACO EUREKA ● UKIAH ● SANTA ROSA 1-800-515-5054 www.lacoassociates.com NO. HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE Date: 12/23/2017 Time: 11:28:34 AM Recharge Area Map BMW CJW - 12/13/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115037 1 Legend UVGB Boundary High Permeability Soils Freshwater Emergent Wetland Freshwater Forested/Shrub Wetland Freshwater Pond Lake Riverine 01.530.75 Miles High Permeability Soils were defined as having a hydrologic soil group of B - Soils having low runoff potential when saturated (NRCS, 2017, Part 630 Hydrology National Engineering Handbook, United States Department of Agriculture, National Resource Conservation Service). Other features were obtained from the National Wetlands Inventory (U.S. Fish and Wildlife Service, 2017, National Wetlands Inventory, Wetlands Mapper). LACO EUREKA ● UKIAH ● SANTA ROSA 1-800-515-5054 www.lacoassociates.com NO. HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) Sulphur Creek McClure Creek Robinson Creek Morrison Creek Doolin Creek McNab Creek Gibson Creek Howard Creek Ackerman Creek East Fork Russian River York Creek Salt Hollow Creek Forsythe Creek West Fork Russian River Russian River West Road Creek Road D Creek Madrone Creek Howell Creek Lake Mendocino Date: 12/23/2017 Time: 10:25:26 AM Surface Water Supply Map BMW CJW CJW 12/20/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115038 1 Legend UVGB Boundary Rivers and Streams Surface Water Bodies 01.530.75 Miles LACO EUREKA ● UKIAH ● SANTA ROSA 1-800-515-5054 www.lacoassociates.com NO. HISTORY/REVISION BY CHK. DATEDRAWN CHECK APPROVED DATE JOB NO. FIGURE Potter Valley Project Diversion Outfall Coyote Dam Outfall Redwood Valley County Water District Diversion Outfall Date: 12/23/2017 Time: 11:41:22 AM Imported Water Map BMW CJW CJW 12/20/2017 7746.09 Ukiah Valley Groundwater Basin Hydrogeologic Conceptual Model Mendocino County Water Agency DWR Grant No. 46000115039 1 Legend UVGB Boundary Imported Water Point of Diversion 0120.5 Miles Point of diversion locations were estimated using Google Earth. The location of the Redwood Valley County Water District point of diversion is approximate. Appendix B. DWR Hydrogeologic Conceptual Model BMP State of California Edmund G. Brown Jr., Governor California Natural Resources Agency John Laird, Secretary for Natural Resources Department of Water Resources Mark W. Cowin, Director Carl A. Torgersen, Chief Deputy Director Office of the Chief Counsel Public Affairs Office Government and Community Liaison Spencer Kenner Ed Wilson Anecita S. Agustinez Office of Workforce Equality Policy Advisor Legislative Affairs Office Stephanie Varrelman Waiman Yip Kasey Schimke, Ass’t Dir. Deputy Directors Gary Bardini Integrated Water Management William Croyle Statewide Emergency Preparedness and Security Mark Anderson State Water Project John Pacheco (Acting) California Energy Resources Scheduling Kathie Kishaba Business Operations Taryn Ravazzini Special Initiatives Division of Integrated Regional Water Management Arthur Hinojosa Jr., Chief Prepared under the direction of: David Gutierrez, Sustainable Groundwater Management Program Manager Rich Juricich, Sustainable Groundwater Management Branch Prepared by: Trevor Joseph, BMP Project Manager Timothy Godwin Dan McManus Mark Nordberg Heather Shannon Steven Springhorn With assistance from: DWR Region Office Staff December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 1 Hydrogeologic Conceptual Model Best Management Practice 1. OBJECTIVE The objective of this Best Management Practice (BMP) is to assist in the use and development of hydrogeologic conceptual models (HCM). The California Department of Water Resources (the Department or DWR) has developed this document as part of the obligation in the Technical Assistance Chapter (Chapter 7) of the Sustainable Groundwater Management Act (SGMA) to support the long-term sustainability of California’s groundwater basins. Information provided in this BMP is meant to provide support to Groundwater Sustainability Agencies (GSAs) when developing a HCM in accordance with the Groundwater Sustainability Plan (GSP) Emergency Regulations (GSP Regulations). This BMP identifies available resources to support development of HCMs. This BMP includes the following sections: 1. Objective. The objective and brief description of the contents of this BMP. 2. Use and Limitations. A brief description of the use and limitations of this BMP. 3. HCM Fundamentals. A description of HCM fundamental concepts. 4. Relationship of HCM to other BMPs. A description of how the HCM relates to other BMPs and is the basis for development of other GSP requirements. 5. Technical Assistance. A description of technical assistance to support the development of a HCM and potential sources of information and relevant datasets that can be used to further define each component. 6. Key Definitions. Definitions relevant for this BMP as provided in the GSP and Basin Boundary Regulations and in SGMA. 7. Related Materials. References and other materials that provide supporting information related to the development of HCMs. 2. USE AND LIMITATIONS BMPs developed by the Department are intended to provide technical guidance to GSAs and other stakeholders. Practices described in these BMPs do not replace or serve as a substitute for the GSP Regulations, nor do they create new requirements or obligations for GSAs or other stakeholders. While the use of BMPs is encouraged, use and/or adoption of BMPs does not equate to an approval determination by the Department. All references to GSP Regulations relate to Title 23 of the California Code December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 2 of Regulations (CCR), Division 2, Chapter 1.5, and Subchapter 2. All references to SGMA relate to California Water Code sections in Division 6, Part 2.74. 3. HCM FUNDAMENTALS A HCM: 1. Provides an understanding of the general physical characteristics related to regional hydrology, land use, geology and geologic structure, water quality, principal aquifers, and principal aquitards of the basin setting; 2. Provides the context to develop water budgets, mathematical (analytical or numerical) models, and monitoring networks; and 3. Provides a tool for stakeholder outreach and communication. A HCM should be further developed and periodically updated as part of an iterative process as data gaps are addressed and new information becomes available. A HCM also serves as a foundation for understanding potential uncertainties of the physical characteristics of a basin which can be useful for identifying data gaps necessary to further refine the understanding of the hydrogeologic setting. An example of a HCM depicted as a three-dimensional block diagram is shown in Figure 1. Figure 1 – Example 3-D Graphic Representing a HCM December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 3 COMMON HCM USES The following provides a limited list of common HCM uses: • Develop an understanding and description of the basin to be managed, specifically the structural and physical characteristics that control the flow, storage, and quality of surface and groundwater • Identify general water budget components • Identify areas that are not well understood (data gaps) • Inform monitoring requirements • Facilitate or serve as the basis for the development, construction, and application of a mathematical (analytical or numerical) model • Refine the understanding of basin characteristics over time, as new information is acquired from field investigation activities, monitoring networks, and modeling results • Provide often highly-technical information in a format more easily understood to aid in stakeholder outreach and communication of the basin characteristics to local water users • Help identify potential projects and management actions to achieve the sustainability goal within the basin HCM IN REFERENCE TO THE GSP REGULATIONS 23 CCR §354.14 (a): Each Plan shall include a descriptive hydrogeologic conceptual model of the basin based on technical studies and qualified maps that characterizes the physical components and interaction of the surface water and groundwater systems in the basin. GSP Regulations 1 require that each GSP include a HCM for the basin reported in a narrative and graphical form that provides an overview of the physical basin characteristics, uses of groundwater in the basin, and sets the stage for the basin setting (GSP §354.14(a)). The GSP Regulations identify the level of detail to be included for the HCM to aid in describing the basin setting for the GSP development and sustainability analysis. 1 http://www.water.ca.gov/groundwater/sgm/pdfs/GSP_Emergency_Regulations.pdf December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 4 The HCM requirements outlined pertain to two main types of information: 1. The narrative description is accompanied by a graphical representation of the basin that clearly portrays the geographic setting, regional geology, basin geometry, general water quality, and consumptive water uses in the basin. 2. A series of geographic maps and scaled cross-sections to provide a vertical layering representation and a geographic view of individual datasets including the topography, geology, soils, recharge and discharge areas, source and point of delivery of imported water supplies, and surface water systems that are significant to management of the basin. A HCM differs from a mathematical (analytical or numerical) model in that it does not compute specific quantities of water flowing through or moving into or out of a basin, but rather provides a general understanding of the physical setting, characteristics, and processes that govern groundwater occurrence within the basin. In that sense, the HCM forms the basis for mathematical (analytical or numerical) model development, and sets the stage for further quantification of the water budget components. The intent of requiring HCMs in the GSP Regulations is not to provide a direct measure of sustainability, but rather to provide a useful tool for GSAs to develop their GSP and meet other requirements of SGMA. 4. RELATIONSHIP OF HCM TO OTHER BMPS The purposes of the HCM in the broader context of SGMA implementation include: • Supporting the evaluation of sustainability indicators, assessing the potential for undesirable results, and development of minimum thresholds; • Supporting identification and development of potential projects and management actions to address undesirable results that exist or are likely to exist in the future; and • Supporting the development of monitoring protocols, networks, and strategies to evaluate the sustainability of the basin over time. The HCM is also linked to other related BMPs as illustrated in Figure 2. This figure provides the context of the BMPs as they relate to various steps to sustainability as outlined in the GSP Regulations. The HCM BMP is part of the Basin Setting development step in the GSP Regulations. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 5 Figure 2 – Logical Progression of Basin Activities Needed to Increase Basin Sustainability HCM development is the first step to understanding and conveying the GSP basin setting. The HCM is also linked to other GSP components (and applicable related BMPs) as illustrated Figure 3. For example, the HCM supports the development of the monitoring networks and activities needed to better understand the distribution and movement of water within a basin, which leads to the initial development and quantification of a water budget. Once the HCM and water budget have been developed, a mathematical (analytical or numerical) model may be built to further evaluate sustainability indicators, assess the probability of future undesirable results, and support basin management decisions as necessary to avoid the occurrence of undesirable results. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 6 Figure 3 – Interrelationship between HCM and Other BMPs and Guidance Documents December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 7 5. TECHNICAL ASSISTANCE This section provides technical assistance to support the development of a basin HCM including potential sources of information and relevant datasets that can be used to develop each HCM requirement. As described in the GSP Regulations Section 354.12, the Basin Setting shall be prepared by or under the direction of a professional geologist or professional engineer. CHARACTERIZING THE PHYSICAL COMPONENTS Each section below is related to the specific GSP Regulation requirements and provides additional technical assistance for the GSA’s consideration. 23 CCR §354.14 (b)(1): The regional geologic and structural setting of the basin including the immediate surrounding area, as necessary for geologic consistency. The regional geologic and structural setting of a basin describes the distribution, extent, and characteristics of the geologic materials present in the basin along with the location and nature of significant structural features such as faults and bedrock outcrops that can influence groundwater behavior in the basin. This type of information can often be found in existing geologic maps and documents published by the Department (specifically Bulletin 118 and 160), the United States Geological Survey (USGS), and other local government agencies (references are also provided in Section 7). Groundwater Management Plans and other technical reports prepared for the basin may also include information of this type. 23 CCR §354.14 (b)(2): Lateral basin boundaries, including major geologic features that significantly affect groundwater flow. Basin boundaries are often geologically controlled and may include bedrock boundaries that define the margins of the alluvial groundwater aquifer system, and therefore represent barriers to groundwater flow. For a map of the Department’s Bulletin 118 groundwater basins and subbasins refer to the Department’s basin boundary website. Other basin boundaries may include rivers and streams, or structural features such as faults. Additionally, basins on the coast can be subject to seawater intrusion, which creates another type of boundary to the freshwater basin. Information on these types of boundaries can also be found in reports prepared by State (California Geological Survey) or federal agencies (USGS) or by local agencies or districts. In addition, the December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 8 presence of seawater along the coastal margin can also reflect the boundary of a coastal basin. 23 CCR §354.14 (b)(3): Definable bottom of the basin. Several different techniques or types of existing information can be used in the evaluation of the definable bottom of the basin and extent of freshwater. Defining the Basin Bottom based on Physical Properties The bottom of the basin may be defined as the depth to bedrock also recognized as the top of bedrock below which no significant groundwater movement occurs. This type of information may be found from reviewing geologic logs from wells drilled for water extraction, as well as from oil and gas exploration wells which tend to be drilled deeper than usable aquifer systems. Defining the Basin Bottom based on Geochemical Properties In many basins of the Central Valley, freshwater is underlain by saltier or brackish water that is a remnant of the marine conditions that were present when the Valley was flooded in the geologic past. Several standards exist that can be used to define the base of freshwater and the bottom of the basin in the Central Valley: • Base of freshwater maps in the Central Valley published by the Department and by USGS • United States Environmental Protection Agency (US EPA) definition for Underground Source of Drinking Water (USDW) The Department plans to release a freshwater map for the Central Valley that depicts the useable bottom of the alluvial aquifer. This map assumes that the base of freshwater is defined by the Title 22 State Water Resources Control Board (SWRCB) upper secondary maximum contaminant level recommendation of 1,000 milligrams per liter (mg/L) total dissolved solids (TDS). The USGS has two base of fresh water maps available in the Central Valley based on 3,000 mg/L TDS. An alternative threshold available to define the bottom of the groundwater basin is the US EPA USDW standard of less than 10,000 mg/L TDS. In some basins, oil and gas aquifers underlie the potable alluvial aquifer or USDW (defined as less than 10,000 mg/L TDS in Title 40, Section 144.3, of the Code of Federal Regulations). In basins where produced water from underlying oil and gas operations is beneficially used within the basin, or injected into the basin’s USDW, the HCM can further characterize the geologic boundaries that separate the USDW from the oil and gas aquifers, and identify the December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 9 “exempted aquifer” portion of the groundwater basin that has been permitted for underground injection control by the SWRCB Oil and Gas Monitoring Program or the Division of Oil, Gas and Geothermal Resources (DOGGR). It should be noted that the definable bottom of the basin should be at least as deep as the deepest groundwater extractions; however, this may not be an appropriate method if it conflicts with other local, State, or Federal programs or ordinances. Finally, consideration should be given to how the bottom of the basin is defined in hydraulically-connected adjacent basins, as this could create additional complexity when developing and implementing GSPs. Defining the Basin Bottom based on Field Techniques Common field techniques used to define the bottom of alluvial basins can be subdivided into techniques utilizing direct measurements and those utilizing indirect measurements. The most common ones are listed below. Direct measurement approaches typically involve drilling of multiple wells through the freshwater-bearing alluvial aquifer sediments and into the underlying lithologic units, whether it is bedrock or alluvium, containing groundwater that does not meet the criteria for potable water or an USDW. Once each borehole has been constructed, several different approaches can be taken to estimate the depth to the basin bottom at that location. Compilation of data from multiple wells can then be used to prepare a contour map of the depth to the basin bottom. Typical direct techniques include: • Installation of multi-port well systems or installation of a nested well array • Continuous profiling of lithology/groundwater quality using TDS, conductivity, or other downhole geophysical techniques • Mapping depth to bedrock from borehole Indirect measurement approaches are typically employed along the ground surface or from helicopters or fixed-wing aircraft. The most common methods used are geophysical techniques or surveys. Typical geophysical techniques that can be used to estimate bedrock depth or groundwater quality profiles include: • Seismic refraction/reflection surveys • Gravity surveys • Magnetic surveys • Resistivity surveys • Radar, including ground penetrating radar • Other Electromagnetic techniques December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 10 23 CCR §354.14 (b)(4): Principal aquifers and aquitards, including the following information: (A) Formation names, if defined. (B) Physical properties of aquifers and aquitards, including the vertical and lateral extent, hydraulic conductivity, and storativity, which may be based on existing technical studies or other best available information. (C) Structural properties of the basin that restrict groundwater flow within the principal aquifers, including information regarding stratigraphic changes, truncation of units, or other features. (D) General water quality of the principal aquifers, which may be based on information derived from existing technical studies or regulatory programs. (E) Identification of the primary use or uses of each aquifer, such as domestic, irrigation, or municipal water supply. Aquifer information is available in geologic reports from the Department and USGS, such as Bulletin 118, and local groundwater management plans and studies. Links to applicable reports are provided below. The USGS maintains very detailed reports and datasets for groundwater quality throughout the state that can be downloaded from their California Water Science Website (http://ca.water.usgs.gov/). The SWRCB also collects and maintains groundwater quality data, accessible through their GeoTracker GAMA website. (http://www.waterboards.ca.gov/gama/geotracker_gama.shtml) In addition, the Regional Water Quality Control Boards, with coordination from the SWRCB, manage groundwater quality programs and data related to the Irrigated Lands Regulatory Program (http://www.swrcb.ca.gov/water_issues/programs/agriculture/). These programs are in the early phases of development, and data are being collected by local entities. As groundwater quality data become available through these programs, they may be a good source of information for HCM and GSP development. The Central Valley Regional Water Quality Control Board and SWRCB, in cooperation with stakeholders and the Central Valley Salinity Coalition, collaborate to review and update the basin plans for the Sacramento and San Joaquin river basins, the Tulare Lake Basin, and the Delta Plan for salinity management. As part of this program, technical reports are being developed and groundwater quality data are being collected in the Central Valley aquifer that provide other sources of information for those basins (http://www.cvsalinity.org/). Uses of groundwater can be found within water quality control plans (known as basin plans), agricultural water management plans (AWMP) and urban water management plans (UWMP), which detail the use of water by agency and by types of beneficial uses. In addition, basin plans describe the water quality objectives and beneficial uses to be protected, with a program of implementation to achieve those objectives. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 11 23 CCR §354.14 (b)(5): Identification of data gaps and uncertainty within the hydrogeologic conceptual model. An assessment of the uncertainty in the HCM components, along with the identification of data gaps of the physical system and water use practices in the basin, are all necessary elements of the HCM. Typical data gaps and uncertainties related to the HCM include the hydraulic properties of the aquifer and aquitard materials, the depth and thickness of various geologic layers, and adequate geographic distribution of groundwater quality data, among others. It is important to adequately evaluate data gaps and uncertainties within a HCM as these data gaps often drive the types and locations of monitoring that should be conducted to reduce uncertainties in these conceptual model components. For example, a portion of a groundwater basin may not be well characterized from previous studies and historic monitoring activities; therefore, there is less readily- available information to define the HCM in that portion of the basin. Specific data collection activities to address these data gaps could then be considered in the development of the GSP. GRAPHICAL AND MAPPING REQUIREMENTS 23 CCR §354.14 (c): The hydrogeologic conceptual model shall be represented graphically by at least two scaled cross-sections that display the information required by this section and are sufficient to depict major stratigraphic and structural features in the basin. In addition to the narrative description of the HCM, another necessary element of a HCM is a graphical representation of the HCM components in the form of at least two geologic cross-sections. A cross-section depicts the vertical layering of the geology and major subsurface structural features in a basin, in addition, but not limited to, other HCM features such as the general location and depth of existing monitoring and production wells and the interaction of streams with the aquifer. The locations selected for cross-section development in a basin are best informed by the sustainability indicators most critical to that basin, as well as the potential for undesirable results to occur. For example, if subsidence is a known issue in a basin, construction of cross-section(s) may be focused in areas where subsidence has occurred or is at risk of occurring. An example of a scaled cross-section is provided in Figure 4. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 12 Figure 4 – Example Scaled Cross-Section Geologic cross-sections should be constructed by a professional geologist, or a person knowledgeable of geologic principles such as the Laws of Superposition, Original Horizontality, cross-cutting relationships, and Walther’s Law. The type of cross-section ranges from "conceptual to highly detailed”, depending on the intended use. The type of cross-section also depends on the type of subsurface data that is available and the reliability of that data. A full understanding of, and appreciation for, the variety of depositional environments, like sequence stratigraphy, is needed to construct accurate geological cross sections. Cross-section construction considerations include, but are not limited to, the following: • Geologic cross-sections are often oriented perpendicular to the strike of the regional bedding. If a line of section oblique to the strike of regional bedding is selected, apparent dip of bedding and structural features should be computed and included in the geologic cross-section. It is important to choose a geologically relevant orientation with respect to strike and dip (and to note whether any of the selected orientations depict an apparent dip much different than the true dip). • The geologic cross-section should not change trend direction, or bend significantly as this can change the relationship of the deposition direction. North and east should be on the right side of the page. If wells logs are projected onto the section the distance they are projected from the section line should be noted. • The location and orientation of the line of geologic cross-section should be presented in plan view on a geologic map. The horizontal distance between boreholes, geologic contacts, structural features, and surface features is interpreted from the scale of the geologic map. The horizontal scale can be enlarged or reduced, preserving the relative distances, based on cross-section December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 13 size. The vertical scale of the cross-section can exceed the horizontal scale (vertical exaggeration) in order to more clearly present the subsurface data. However, the scale should be chosen without undue vertical exaggeration. • Subsurface lithology and structural features should be projected from surface contacts at the dip angle (or apparent dip) reported on the geologic map. Subsurface contacts may be correlated/interpreted between boreholes based on available lithologic logs and professional judgement. The cross-sections should be tied where they cross and to the geologic map at formation contacts. • Cross-sections should include major aquifer and aquitard units, but it may not be necessary to include all lithologic beds on the cross-section. • The geologic cross-section should include information provided on lithologic logs for boreholes along the line of section. Information for wells off-set from the line of section can be projected onto the cross-section. The maximum distance for projection of data onto the cross-section will be dependent upon the scale; professional judgement should be used in the selection of the maximum projection distance. The distance for projection of data should be somewhat dependent on the reasonableness one can infer that the units or features continue with some level of certainty. Conversely, if there is uncertainty, dashed lines or question marks are often applied to denote uncertainty. • The level of detail and quality of available subsurface lithologic logs will vary between boreholes. The quality of individual lithologic logs should be considered when correlating subsurface borehole information. • Where two cross-section lines intersect, the subsurface interpretations presented on the geologic cross-sections should be consistent at the intersection. • The data used for horizon boundaries should be shown and posted for reference; and any references used to depict the cross-sections should be cited. If known, other details should also be included in hydrogeologic cross sections, such as: (1) static water level of each aquifer; (2) screened intervals; (3) total depth of the boring/well; (4) availability of geophysical logs; and (5) type of drilling method. Additional notation on the cross-section may also be helpful for illustration. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 14 23 CCR §354.14 (d) Physical characteristics of the basin shall be represented on one or more maps that depict the following: (1) Topographic information derived from the U.S. Geological Survey or another reliable source. (2) Surficial geology derived from a qualified map including the locations of cross sections required by this Section. (3) Soil characteristics as described by the appropriate Natural Resources Conservation Service soil survey or other applicable studies. (4) Delineation of existing recharge areas that substantially contribute to the replenishment of the basin, potential recharge areas, and discharge areas, including significant active springs, seeps, and wetlands within or adjacent to the basin. (5) Surface water bodies that are significant to the management of the basin. (6) The source and point of delivery for imported water supplies. Geographical representations of the distribution of major data elements in a groundwater basin in map form help illustrate the layout of data and information presented in the HCM. The data for these maps are generally available from various sources such as GIS Shapefiles that can be overlain on a basin-wide base map. As stated in the GSP Regulations, physical characteristics of the basin need to be displayed on maps. Information is provided on the types of datasets readily available for mapping. • Topographic information can be found from online USGS topographic maps or more detailed high resolution Digital Elevation Model (DEM) mapping GIS datasets. There are several sources of topographic and DEMs available online, such as the ones provided in Section 7. • In addition, the ESRI ArcGIS platform also includes DEM data available for use in conjunction with the ESRI GIS software. • Surficial Geologic information can be downloaded from the California Geological Survey (CGS) and USGS from their interactive mapping tool. o CGS - http://maps.conservation.ca.gov/cgs/gmc/ o USGS - http://ngmdb.usgs.gov/ngmdb/ngmdb_home.html The map that is produced to illustrate the surficial geology of the basin should also include the location of the cross-sections. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 15 • The National Resource Conservation Service (NRCS) maintains soil data and Shapefiles nationwide on a county basis available at their website: http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx. For additional related soil characteristics in California, see the UC Davis soil interactive maps (http://casoilresource.lawr.ucdavis.edu/). • Recharge and discharge areas of groundwater are generally not well mapped. This type of information may be available from local and regional groundwater management planning documents, or larger reports form the Department and USGS. Additional recharge maps in California have been developed by the California Soil Resource Lab at UC Davis – The following link is to their Soil Agricultural Groundwater Banking Index (SAGBI): http://casoilresource.lawr.ucdavis.edu/sagbi/ • Surface water mapping data can be downloaded from ESRI base maps within ArcGIS, or downloaded from the National Hydrography Datasets (NHD) datasets: http://viewer.nationalmap.gov/viewer/nhd.html?p=nhd • Water supplies imported into a basin from state, federal, or local projects need to be mapped for the HCM. This information is generally available from the major suppliers of surface water such as the Department, United States Bureau of Reclamation (USBR), and local water and irrigation districts. Additional useful information to be mapped may include: • Groundwater elevation contour maps show the spatial distribution of groundwater elevations and help identify areas of low and high groundwater level areas within a basin. Elevation contour maps can be created from water level data collected from wells that are screened within the same principal aquifers. Information on water level data interpolation to create contour maps can be found in Tonkin et. al (2002). • Land use maps detail the agricultural and urban land uses, and the distribution of natural vegetation, including potentially groundwater-dependent ecosystems. Land use maps shall use the Department land use classification scheme and maps provided by the Department. An example of a geologic map is provided in Figure 5. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 16 Figure 5 – Example Geologic Map December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 17 TYPICAL FLOW OF GRAPHICAL HCM DEVELOPMENT The HCM requirements outlined in the GSP Regulations pertain to two main types of information: 1. Narrative description of the basin, which can be accompanied by a three- dimensional graphic illustration of the HCM to complement the narrative; and 2. At least two scaled cross-sections and geographic maps to provide vertical layering representation and a geographic view of individual datasets, respectively. The typical flow of graphical HCM development is presented in Figure 6. This figure shows the level of technical representation and detail, from basic cartoon-type representation, to a geographic representation map, to a scaled vertical cross-section that provides more subsurface detail for the HCM. Figure 6 – Steps to Developing Graphic Representations of the HCM December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 18 6. KEY DEFINITIONS The key definitions related to HCM development outlined in applicable SGMA code and regulations are provided below for reference. SGMA Definitions (California Water Code §10721) • “Groundwater recharge” or “recharge” means the augmentation of groundwater by natural or artificial means. • “Recharge area” means the area that supplies water to an aquifer in a groundwater basin. Groundwater Basin Boundaries Regulations (California Code of Regulations §341) • “Aquifer” refers to a three-dimensional body of porous and permeable sediment or sedimentary rock that contains sufficient saturated material to yield significant quantities of groundwater to wells and springs, as further defined or characterized in Bulletin 118. • “Hydrogeologic conceptual model” means a description of the geologic and hydrologic framework governing the occurrence of groundwater and its flow through and across the boundaries of a basin and the general groundwater conditions in a basin or subbasin. • “Qualified map” means a geologic map of a scale no smaller than 1:250,000 that is published by the U. S. Geological Survey or the California Geological Survey, or is a map published as part of a geologic investigation conducted by a state or federal agency, or is a geologic map prepared and signed by a Professional Geologist that is acceptable to the Department. • “Technical study” means a geologic or hydrologic report prepared and published by a state or federal agency, or a study published in a peer-reviewed scientific journal, or a report prepared and signed by a Professional Geologist or by a Professional Engineer. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 19 Groundwater Sustainability Plan Regulations (California Code of Regulations §351) • “Basin setting” refers to the information about the physical setting, characteristics, and current conditions of the basin as described by the Agency in the hydrogeologic conceptual model, the groundwater conditions, and the water budget, pursuant to Subarticle 2 of Article 5. • “Best available science” refers to the use of sufficient and credible information and data, specific to the decision being made and the time frame available for making that decision, that is consistent with scientific and engineering professional standards of practice. • “Data gap” refers to a lack of information that significantly affects the understanding of the basin setting or evaluation of the efficacy of Plan implementation, and could limit the ability to assess whether a basin is being sustainably managed. • “Principal aquifers” refer to aquifers or aquifer systems that store, transmit, and yield significant or economic quantities of groundwater to wells, springs, or surface water systems. • “Uncertainty” refers to a lack of understanding of the basin setting that significantly affects an Agency’s ability to develop sustainable management criteria and appropriate projects and management actions in a Plan, or to evaluate the efficacy of Plan implementation, and therefore may limit the ability to assess whether a basin is being sustainably managed. • “Water source type” represents the source from which water is derived to meet the applied beneficial uses, including groundwater, recycled water, reused water, and surface water sources identified as Central Valley Project, the State Water Project, the Colorado River Project, local supplies, and local imported supplies. • “Water use sector” refers to categories of water demand based on the general land uses to which the water is applied, including urban, industrial, agricultural, managed wetlands, managed recharge, and native vegetation. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 20 7. RELATED MATERIALS This section provides a list of related materials including general references, standards, guidance documents, and selected case studies and examples pertinent to the development of HCMs. For the items identified, available links to access the materials are also provided. In addition, common data sources and links to web-materials are also provided. By providing these links, DWR neither implies approval, nor expressly approves of these documents. It should also be noted that existing Groundwater Management Plans (GMP), Salt & Nutrient Management Plans (SNMP), Urban Water Management Plans (UWMP), Drinking Water Source Assessment Plans (DWSAP), Agricultural Water Management Plans (AWMP), and Integrated Regional Water Management Plans (IRWMP) may be useful references in the development of HCMs. To the extent practicable, GSAs should utilize and build on available information. STANDARDS • ASTM D5979 – 96 (2014) Standard Guide for Conceptualization and Characterization of Groundwater Systems REFERENCES FOR FURTHER GUIDANCE Basin Boundary Modifications web page. California Department of Water Resources. http://www.water.ca.gov/groundwater/sgm/basin_boundaries.cfm Accessed December 2016. California Geological Survey web page. California Department of Conservation. http://www.quake.ca.gov/ Accessed December 2016. California Soil Resource Lab web page. University of California, Davis. https://casoilresource.lawr.ucdavis.edu/ Accessed December 2016. California Water Plan (Bulletin 160). California Department of Water Resources. http://www.water.ca.gov/waterplan/cwpu2013/final/index.cfm Accessed December 2016. California Water Science Center. U.S. Geological Survey. http://ca.water.usgs.gov/ Accessed December 2016. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 21 California’s Groundwater, Bulletin 118. California Department of Water Resources. http://water.ca.gov/groundwater/bulletin118.cfm Accessed December 2016. Central Valley Salinity Alternatives for Long-term Sustainability web page. Central Valley Salinity Coalition. http://www.cvsalinity.org/ Accessed December 2016. European Commission. 2010. Common Implementation Strategy for the Water Framework Directive (2000/60/EC). Guidance Document No. 26. Guidance on Risk Assessment and the Use of Conceptual Models for Groundwater. Technical Report – 2010-042. Fulton, J.W., et. al. 2005. Hydrogeologic Setting and Conceptual Hydrologic Model of the Spring Creek Basin, Centre County, Pennsylvania, June 2005. USGS Scientific Investigation Report 2005-5091. http://pubs.usgs.gov/sir/2005/5091/sir2005-5091.pdf Geologic Map of California (GMC). California Department of Conservation. http://maps.conservation.ca.gov/cgs/gmc/ Accessed December 2016. Groundwater Ambient Monitoring and Assessment Program (GAMA) web page. State Water Resources Control Board. http://www.waterboards.ca.gov/gama/geotracker_gama.shtml Accessed December 2016. Interactive Fault Map. U.S. Geological Survey. http://earthquake.usgs.gov/hazards/qfaults/map/#qfaults Accessed December 2016. Irrigated Lands Regulatory Program web page. State Water Resources Control Board. http://www.swrcb.ca.gov/water_issues/programs/agriculture/ Accessed December 2016. National Geologic Map Database. U.S. Geological Survey. https://ngmdb.usgs.gov/ngmdb/ngmdb_home.html Accessed December 2016. National Map Hydrography. U.S. Geological Survey. https://viewer.nationalmap.gov/viewer/nhd.html?p=nhd Accessed December 2016. Oil and Gas Monitoring Program web page. State Water Resources Control Board. http://www.waterboards.ca.gov/water_issues/programs/groundwater/sb4/index.shtml Accessed December 2016. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 22 Teresita Betancur V., Carlos Alberto Palacio T. and John Fernando Escobar M. 2012. Conceptual Models in Hydrogeology, Methodology and Results - A Global Perspective, Dr. Gholam A. Kazemi (Ed.), ISBN: 978-953-51-0048-5, InTech, Available from: http://www.intechopen.com/books/hydrogeology-a-globalperspective/conceptual- models-in-hydrogeology-methodologies-and-results Tonkin, M. and Larson, S. 2002. Kriging Water Levels with a Regional-Linear and Point- Logarithmic Drift, Ground Water, March-April 2002. Toth, J. 1970. A conceptual model of the groundwater regime and the hydrogeologic environment. Journal Of Hydrology, Volume 10, Issue 1. February. doi:10.1016/0022- 1694(70)90186-1 Web Soil Survey. U.S. Department of Agriculture Natural Resources Conservation Service. http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx Accessed December 2016. REFERENCES FOR CROSS SECTIONS Suggestions to Authors of the Reports of the United States Geological Survey, Seventh Edition, 1991. See Section named Cross Sections and Stratigraphic Sections and Preparing Maps and Other Illustrations, with a subsection titled Cross Sections. Manual of Field Geology, Robert Compton, 1962. Chapter 11, Preparing Geologic Reports, Section 11-10 Detailed Geologic Maps and Cross Sections. Walker, Roger G. (editor), 1981, Facies Models, Geological Association of Canada Publications, Toronto, Canada, 211 pages. Reading, H.G. (editor), 1978, Sedimentary Environments and Facies, Elsevier Press New York, 569 pages. Krumbein, K.C. and L.L. Sloss. 1963, Stratigraphy and Sedimentation, W.H. Freeman and Company, San Francisco, 660 pages. December 2016 Hydrogeologic Conceptual Model BMP California Department of Water Resources 23 DATA SOURCES Geology reports: Geology of the Northern Sacramento Valley, CA: http://www.water.ca.gov/pubs/geology/geology_of_the_northern_sacramento_valley__ california__june_2014- web/geology_of_the_northern_sacramento_valley__california__june_2014__updated_09 _22_2014__website_copy_.pdf Digital Elevation Models (DEMs): • http://www.opendem.info/opendem_client.html • http://viewer.nationalmap.gov/basic/?basemap=b1&category=ned,nedsrc&title=3 DEP%20View • http://www.brenorbrophy.com/California-DEM.htm. Appendix C. Cross Section Well Logs Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.d Date: 10/15/19 To: Board of Directors Subject: Presentation, Discussion and Possible Action Regarding the Regarding the Data Management System Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will receive an update and presentation from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan focusing on the Data Management System. Recommended Action: Provide direction to staff regarding the Data Management System. Background: On June 14, 2018, the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) recommended approval of a contract with Larry Walker and Associates for the development of the Ukiah Valley Groundwater Sustainability Plan (GSP). On July 10, 2018, the Mendocino County Water Agency Board of Directors approved the contract with Larry Walker and Associates. On September 13, 2018, Larry Walker and Associates present an overview of the project and schedule to solicit feedback from the Board. Larry Walker and Associates will be presenting to the Board on a regular basis to review components of the GSP for feedback and approval. Fiscal Summary: N/A Action: ___________________________________________________ Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Motion:_____________________ 2nd:__________________________ Page 2 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.e Date: 10/15/19 To: Board of Directors Subject: Presentation, Discussion and Possible Action Regarding the Regarding the Water Budget Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will receive an update and presentation from Larry Walker and Associates regarding components of the Ukiah Valley Groundwater Sustainability Plan focusing on the Water Budget. Recommended Action: Provide direction to staff regarding the Water Budget. Background: On June 14, 2018, the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) recommended approval of a contract with Larry Walker and Associates for the development of the Ukiah Valley Groundwater Sustainability Plan (GSP). On July 10, 2018, the Mendocino County Water Agency Board of Directors approved the contract with Larry Walker and Associates. On September 13, 2018, Larry Walker and Associates present an overview of the project and schedule to solicit feedback from the Board. Larry Walker and Associates will be presenting to the Board on a regular basis to review components of the GSP for feedback and approval. Fiscal Summary: N/A Action: ___________________________________________________ Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Motion:_____________________ 2nd:__________________________ Page 2 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary Item No.: 6.f Date: 10/15/19 To: Board of Directors Subject: Adoption of a Resolution Authorizing the General Manager of the Mendocino County Water Agency to Apply for the Department of Water Resources Proposition 68 2019 Sustainable Groundwater Management Grant Program Planning – Round 3 Grant on Behalf of the Agency Consent Agenda Regular Agenda Noticed Public Hearing Summary: The Board will consider adoption of a Resolution authorizing the Mendocino County Water Agency to submit a Proposition 68 grant application on the Agency’s behalf. Recommended Action: Adopt Resolution authorizing the General Manager of the Mendocino County Water Agency to apply for the Department of Water Resources Proposition 68 2019 Sustainable Groundwater Management Grant Program Planning – Round 3 Grant on behalf of the Agency. Background: On April 18, 2017, the Mendocino County Water Agency executed a Joint Powers Agreement joining the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) and acting as the Agency's Treasurer and Controller. In June of 2018 the Board of Directors approved a contract with Larry Walker and Associates for the development of Phase 2 of the Ukiah Valley Groundwater Sustainability Plan and fund the contract with the Proposition 1 Groundwater Sustainability Planning Grant. The Water Agency on behalf of the UVBGSA is preparing a grant application for up to $1,300,000 in funds to complete this project through Proposition 68. The funding will be used in upgrading the groundwater model to a USGS model that will be compatible with the larger Russian River Watershed model, additional education and outreach focused on tribes and disadvantaged communities and building a monitoring network for state required reporting within our CASGEM program. Page 1 of 2 Ukiah Valley Basin Groundwater Sustainability Agency Agenda Summary The Proposition 68 grant guidelines requires a resolution from both the UVBGSA Board of Directors and the Mendocino County Water Agency Board of Directors. The resolution authorizes an application be made to Department of Water Resources and allows the Water Agency General Manager or designee to enter into an agreement to receive a grant for the project. The Mendocino County Water Agency is current drafting the grant, which is due to the State on November 1, 2019. Fiscal Summary: N/A Action: ___________________________________________________ Motion:_____________________ 2nd:__________________________ Page 2 of 2 RESOLUTION NO. 19- RESOLUTION OF THE UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY AGENCY BOARD OF DIRECTORS AUTHORIZING THE GENERAL MANAGER OF THE MENDOCINO COUNTY WATER AGENCY TO ENTER INTO AN AGREEMENT TO RECEIVE A PROPOSITION 68 GROUNDWATER SUSTAINABILITY PLANNING GRANT FOR THE DEVELOPMENT OF THE UKIAH VALLEY BASIN GROUNDWATER SUSTAINABILITY PLAN WHEREAS, the Ukiah Valley Basin Groundwater Sustainability Agency (Agency) desires the Mendocino County Water Agency to apply for the Department of Water Resources Proposition 68 2019 Sustainable Groundwater Management Grant Program Planning – Round 3 Grant on behalf of the Agency; and WHEREAS, the Mendocino County Water Agency upon grant award is required to enter into an agreement with the State of California, Department of Water Resources, in order to obtain funds for the Proposition 68 Groundwater Sustainability Planning Grant for Phase III of the Ukiah Valley Basin Groundwater Sustainability Plan; and WHEREAS, the Agency acknowledges the benefits and responsibilities to be shared by both parties to said agreement; and WHEREAS, this agreement is to provide funding for the development of a groundwater management plan for the County, within the Ukiah Valley Groundwater Basin; and WHEREAS, the Board of Directors of the Ukiah Valley Basin Groundwater Sustainability Agency has read the proposed agreement between the State of California, Department of Water Resources and the Mendocino County Water Agency; and WHEREAS, this resolution is for the purpose of identifying the authorized representative to execute an agreement with the State of California for a Proposition 68 Groundwater Planning Grant Program. NOW, THEREFORE, BE IT RESOLVED by the Ukiah Valley Basin Groundwater Sustainability Agency, that application be made to the California Department of Water Resources to obtain a grant under the 2019 Sustainable Groundwater Management (SGM) Grant Program Planning – Round 3 Grant pursuant to the Water Quality, Supply, and Infrastructure Improvement Act of 2014 (Proposition 1) (Wat. Code, § 79700 et seq.) and/or the California Drought, Water, Parks, Climate, Coastal Protection, and Outdoor Access For All Act of 2018 (Proposition 68) (Pub. Resources Code, § 80000 et seq.), and to enter into an agreement to receive a grant for: Phase III of the Ukiah Valley Basin Groundwater Sustainability Plan. The General Manager of the Mendocino County Water Agency, or designee is hereby authorized and directed to prepare the necessary data, conduct investigations, file such application, and execute a grant agreement with California Department of Water Resources. The foregoing Resolution introduced by Director , seconded by Director , and carried this day of , 2019, by the following vote: AYES: NOES: ABSENT: WHEREUPON, the Chair declared said Resolution adopted and SO ORDERED. _________________________________ CARRE BROWN, Chair Ukiah Valley Basin Groundwater Sustainability Agency ATTEST: ______________________________ Brandi Brown Secretary Ukiah Valley Basin Groundwater Sustainability Agency