Loading...
HomeMy WebLinkAboutDraft_2020 Nov 18 TAC Meeting PresentationDRAFT Ukiah Valley Groundwater Sustainability Plan Development Update November 18, 2020 Ukiah Valley Basin Groundwater Sustainability Agency Technical Advisory Committee DRAFT ◼Update on Monitoring Networks, Instrumentation, and Installations ◼Future Scenarios ◼Initial Monitoring Network Design: Chronic Lowering of Groundwater Levels ◼Initial Sustainable Management Criteria Development for Chronic Groundwater Level Decline (time permitting) Outline DRAFT ◼Update on Monitoring Networks, Instrumentation, and Installations ◼Future Scenarios ◼Initial Monitoring Network Design: Chronic Lowering of Groundwater Levels ◼Initial Sustainable Management Criteria Development for Chronic Groundwater Level Decline (time permitting) Outline DRAFTUpdate on Monitoring Networks, Instrumentation, and Installations ◼Drilling Wells ⚫TSS wells ( 3-4 wells) are awaiting the final written agreements to be submitted to the DWR. ◼Existing Wells Instrumentation ⚫4 wells have been instrumented in southern Ukiah ⚫Agreements are being reached with owners in northern Ukiah and Redwood Valley for instrumentation of 4-5 wells. ⚫1 or 2 installation trips will be scheduled as soon as these agreements are in place and we will be almost done. ◼Streamflow gages ⚫We are officially starting the installation of the gages on Russian River and Forsythe Creek with the help of CLSI. DRAFT ◼Update on Monitoring Networks, Instrumentation, and Installations ◼Future Scenarios ◼Initial Monitoring Network Design: Chronic Lowering of Groundwater Levels ◼Initial Sustainable Management Criteria Development for Chronic Groundwater Level Decline (time permitting) Outline DRAFT Future Scenarios: ◼Direction from the Board on Nov 12: ⚫Choose scenarios that only highlight higher impacts to the water system and then run additional scenarios that directly involve management actions ⚫Focus on a plan that is more likely to be approved by the DWR and addresses requirements outlined by the department. Fu t u r e S c e n a r i o s Required Future Baseline Climate Change Additionally Selected Helps with Understanding of the Basin Helps Set SMCs Investigates Management Actions DRAFT Future Scenario Survey: Future Baseline ◼In order to generate a representative future baseline scenario, we need to form a 50-year period from the basin’s historical record. What would be the most representative 50-year baseline? Major Comments: ◼Last 50-years may be the least conservative because it does not take into account the most recent period→suggest to repeat the last 25 years ◼Either 25-50 year periods are fine but we should look at how the water years are assigned with the Gamma Distribution. DRAFT Future Scenario Survey: Climate change Is:Is not: Climate time-period analysis || Conditions at the end of the simulation and each year in between are not the expected conditions at those years rather how things may look like around 2030 or 2070 Transient analysis || Forecast aims to produce a timeseries of results that are representative or the progression of changes into the future. Suitable for relative comparison to the historical simulations and assessing statistical trends and summary statistics Suitable to be considered as specific occurrences in points of time Suitable to single out changes due to climate change impacts Fully capable to project changes to interannual phenomena like changes to seasonality, rainfall duration and intensity, etc. due to climate change Straight forward and recommended by the DWR and widely used by other basins Being used or supported by Sonoma Water in their basins. Already including a group of GCM/RCP Scenarios in its development Equivalently justifiable as using single transient scenarios unless they are studied for the local region ◼DWR methodology for climate change simulation through precipitation and ET multipliers: DRAFT Future Scenario Survey: Climate change ◼Do you agree with using the DWR recommended approach to conduct the climate change simulations for the Ukiah Valley Basin GSP? If not, please provide your suggestion while also considering that additional time and budget needed to conduct different approaches may become significant. Major Comments: ◼A transient method would be more appropriate for evaluating potential impacts to Lake Mendocino and surface water flows in the main stem Russian River. ◼Include additional climate change simulations as may be available to the consultants and deemed relevant for this basin. DRAFT Future Scenario Survey: Changes to PVP ◼There is an expectation that PVP operations would change during the implementation period of the GSP. This scenario, or a set of scenarios, would simulate how those changes would impact the basin and the beneficial uses. Major Comments: ◼All respondents say it is helpful and we can run Sonoma Water scenarios. ◼No diversion, partial (winter only) diversion, and run of the river scenario should be run. ◼Everybody agrees it would not be immediate, responses from 5 to 15 years. ◼Everybody thinks we should combine it with other scenarios, including climate change, fish flow habitat, DRAFT Future Scenario Survey: summary of PVP scenarios ◼LWA to conduct bookending scenarios to gauge the impacts of the PVP scenarios to the extent possible. ◼Final 3 scenarios that were agreed upon are: ⚫Removal of the dam and no additional flows (worst-case scenario) ⚫No change ⚫Run of the river ◼All scenarios will be set up to start happening in 15 years ◼Difficult issue is to estimate appropriate flows from CVD and PVP for different scenarios. DRAFT Scenario What we are required to have What we have now or plan to have for GSP Submittal in Jan 2020 Future Baseline A 50-year representation 50-year repeat of historical baseline (could be changed to two 25-year) Climate Change Capture impacts of climate change using best available science and knowledge 2 DWR provided climate period analyses 2030 & 2070 CVD Releases Best available science and information: forecast appropriate releases for each scenario Historical and future baseline using hard input measured by gages/ Future changes taken directly from Sonoma Water ResSim outputs PVP PVP outputs based on reasonable possibilities to assist with setting SMCs and developing management actions Historical/future baseline input to basin from gages/ Scenarios taken directly from Sonoma Water ResSim outputs Overall for other future scenarios Best available science and accurate representation of basin and possibilities to develop SMCs and MAs We are reliant on historical inputs and ResSim outputs for combination of scenarios assuming no major discrepancies between their flow and diversion calculations and our model Can be fit in our current budget Will be done unless evaluation of input files hints at inconsistencies Future Scenario: To be run for GSP Submittal DRAFT Scenario What we are required to have Proposed/possible Improvements for 2027 Milestone Future Baseline A 50-year representation Coordinate with Sonoma Water to use similar water years and similar setup as USGS Model Climate Change Capture impacts of climate change using best available science and knowledge Transient simulation of 50-year period using GCM/RCP/Downscaling method scenarios to be used in Sonoma basins and the Ukiah basin CVD Releases Best available science and information: forecast appropriate releases for each scenario Using compatible Sonoma ResSim with matching climate data and diversions as GSFLOW model; Coordinated with USGS model PVP PVP outputs based on reasonable possibilities to assist with setting SMCs and developing management actions Using compatible Sonoma ResSim with matching climate data and diversions as GSFLOW model; Coordinated with USGS model Overall for other future scenarios Best available science and accurate representation of basin and possibilities to develop SMCs and MAs Rerun impactful scenarios or additional scenarios with updated ResSim outputs and compare with USGS model Future Scenario: To be Considered for the Next Stage DRAFT Questions? DRAFT Scenarios related to Projects and Management Actions Major Comments: ◼Majority of respondents say it is not helpful/maybe helpful or not sure. ◼Review Upper Russian River/Lake Mendocino Reliability report. ◼Increased utilization of water rights in 20 years may cover for these scenarios. Major Comments: ◼Majority of respondents say it is a helpful scenario. ◼Review Upper Russian River/Lake Mendocino Reliability report. ◼Not everyone agrees on the trend or if historical trends are representative. ◼Combine with PVP, land conversion, and climate change. Major Comments: ◼Majority of respondents say it is a helpful scenario. ◼Scale and location answer did not converge. ◼Step-wise and in small steps was emphasized for when it may happen. ◼Combine with PVP, RW, Ag land conversion, and climate change. Major Comments: ◼Majority of respondents say it is a helpful scenario. ◼Follow the City’s plan. Changes in Land Use and Ag Urban expansion, population growth, and increase in demand Recharge Projects Recycled Water DRAFT Discussion on Scenarios Prioritization ◼Which scenario(s) would be more helpful for planning? ◼What scenarios are better to be run in coordination with other scenarios? ◼Other comments? DRAFT ◼Update on Monitoring Networks, Instrumentation, and Installations ◼Future Scenarios ◼Initial Monitoring Network Design: Chronic Lowering of Groundwater Levels ◼Initial Sustainable Management Criteria Development for Chronic Groundwater Level Decline (time permitting) Outline DRAFT Updates from the Last Meeting ◼We searched for WCRs and well information for CASGEM and water supply wells. We are still missing these information for several wells. ◼We reassigned CASGEM wells according to WCRs and HCM refined geological maps. This led to a few wells being moved from Aquifer I to Aquifer II. ◼Due to narrow and shallow nature of the Aquifer I, it seems we need to move DWR wells to Aquifer II. We are missing WCRs for all of them as of now. DRAFT Principal Aquifers ◼We currently have 3 principal aquifers resembling different geological units. This is based on initial HCM designations that we were directed to follow. ◼Principal aquifers should include corresponding monitoring networks and SMCs. ◼We are working with our partners at GEI on converting from three to one or two principal aquifer systems: ⚫There are no significant clay lenses/barriers to vertical flow in the basin that separate aquifers ⚫This does not translate to any changes to the geological properties of the basin ⚫This can be separate from integrated model layering ⚫Aquifer III is not a productive aquifer and cannot be clearly distinguished from aquifer II in most areas of the basin due to lack of information ⚫Having fewer principal aquifers means less data gaps; if the conversion to fewer aquifers does not translate to loss of information itself. ⚫Changes will need some minor revisions to the text of the HCM ◼For now, we still move forward based on our current designations of 3 aquifers. DRAFT Monitoring Networks: Density and Extent De t e r m i n i n g F a c t o r s Aquifer Characteristics GW pumpage and use Impacts to BUs Fluctuation and variability Proximity to projects or adjacent basins Multi-SI monitoring Access and safety “There is no definitive rule for the density of groundwater monitoring points needed in a basin.” UVGB: 59 sq miles Conservatively, we can assume just as a direction that we need 1 well per each 25 sq. miles (radius of less than 3 miles) DRAFT ◼We want to rely on existing CASGEM and what we drill and/or instrument. ◼What we include needs to have: ⚫WCR/Drillers Log or equivalent ⚫Construction information: Well depth and perforations ◼Not all the wells on the right yet have these data, we may need to change them. ◼We want DWR wells to be included for our RMPs. But they will only cover one aquifer (Aquifer II). ◼Nested well in Redwood Valley is not yet 100%. ◼Drilled well in Central Ukiah is not yet 100%. Existing and Planned Monitoring Network for Chronic Lowering of Groundwater Levels DRAFT ◼We are missing WCRs for 3 of the wells. ◼We may instrument a WWTP well if needed that can substitute UV-28 and/or the drilled well. It will be automatically included in the network. ◼Drilled well in Redwood Valley is not 100%. Possible Monitoring Network for Aquifer I ◼We will have a good coverage for the entire basin based on 3-mile radius with wells to spare. ◼Aquifer I has data gaps. We lack long- term data for SMCs… ◼GW Level SMC and monitoring network for this aquifer is tied to SW depletion. DRAFT ◼We are missing WCRs for a few of the wells including all DWR wells. ◼We already instrumented UV-26, UV-34, and will be instrumenting UV-15 (maybe UV-19 if we do not drill the nested well in Redwood Valley) Possible Monitoring Network for Aquifer II ◼We will have a good coverage for the entire basin based on 3-mile radius with wells to spare. The drainage of the basin is our data gap. ◼DWR wells are our RMPs and long-term data. ◼This Aquifer may be combined with Aquifer III. DRAFT ◼This aquifer may be combined with Aquifer II. ◼We have significant data gaps and are relying on our nested well drillings. ◼Conversion to a single aquifer with Aquifer II will cover data gaps and makes setting SMCs and designing monitoring networks easier and more straight- forward. Possible Monitoring Network for Aquifer III ◼While the coverage seems sufficient, there are no alternatives, and we have to have all these four wells in our network. DRAFT Questions or Comments? Questions? DRAFT ◼Update on Monitoring Networks, Instrumentation, and Installations ◼Future Scenarios ◼Initial Monitoring Network Design: Chronic Lowering of Groundwater Levels ◼Initial Sustainable Management Criteria Development for Chronic Groundwater Level Decline (time permitting) Outline DRAFT Setting Sustainable Criteria ◼Consider: ⚫UVB does not suffer from chronic lowering of GW levels, water levels are relatively stable ⚫Seasonality is very important ⚫This SI needs to interact with the SI for SW Depletion and GDEs ⚫Operational flexibility is very important due to seasonal changes and stable conditions ⚫Aquifer-specific and region-specific criteria must be set ⚫A focus on multi-year droughts was proposed in the last working group meeting ◼Follow this link to see for yourself: https://larrywalkerassociates.github.io/sites/data/ukiah_gwl/ DRAFT Setting Sustainable Criteria ◼Discuss and decide: ⚫Is there a need for defining hydrogeologic zones or management areas? ⚫What is the most suitable method(s) applicable to UVB ⚫Trend may not be appropriately applicable to all zones in UVB ⚫What are the impacts of what we are setting? ➢Who is impacted? ➢To what extent? Relevant population impacted and for how long? Can they recover? ➢Can we define actions that would help those impacted? If not, should we let those impacts occur? ➢What impacts GSA may have control over? What impacts it does not? DRAFT Possible Sustainable Criteria for Aquifer II ◼Undesirable Result: Significant and unreasonable reduction of long-term availability of groundwater for domestic, municipal, and agricultural users of water. ◼Identification of Undesirable Results: More than 33% of RMPs (translates to 2 or more wells currently, assuming we will have 3 RMPs) exceed their minimum thresholds for two consecutive years ◼Minimum Threshold: Average of the two lowest consecutive spring level measurements during the most recent multi-year draught (2012-2016) ◼Measurable Objective: Spring measurement in 2015 (Spring of 2015) DRAFT Redwood Valley -392962N1232047W001 (Aquifer II) ◼Average: ⚫Average fall: 15.7 ⚫Average spring: 9.2 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Fall: 17.4-17 (2013-15) ⚫Fall drop from average: ~2 ⚫Lowest Spring: 13.6-12 (2014- 15) ⚫Spring drop from average: ~4.5 ⚫Largest Seasonal Change: 9.1 ◼Historical Min: ⚫Fall: 17.4 ⚫Spring: 13.6 ◼Shallowest well depth nearby: ⚫80 ft nearby ⚫18 ft in Redwood Valley •Spring Meas. •13 ft-bgsMT •2015 Spring Meas. •12 ft-bgsMO DRAFT Redwood Valley -392962N1232047W001 (Aquifer II) ◼Average: ⚫Average fall: 15.7 ⚫Average spring: 9.2 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Fall: 17.4-17 (2013-15) ⚫Fall drop from average: ~2 ⚫Lowest Spring: 13.6-12 (2014- 15) ⚫Spring drop from average: ~4.5 ⚫Largest Seasonal Change: 9.1 ◼Historical Min: ⚫Fall: 17.4 ⚫Spring: 13.6 ◼Shallowest well depth nearby: ⚫80 ft nearby ⚫18 ft in Redwood Valley •Spring Meas. •13 ft-bgsMT •2015 Spring Meas. •12 ft-bgsMO DRAFT Central Ukiah Valley -15N12W08L001M (Aquifer II) ◼Average: ⚫Average fall: 25 ⚫Average spring: 19 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Fall: 26.3-30.1 (2014-15) ⚫Fall drop from average: ~5 ⚫Lowest Spring: 19.3-25.3 (2012-13) ⚫Spring drop from average: ~6 ⚫Largest Seasonal Change: 9.8 ◼Historical Min: ⚫Fall: 30.1 ⚫Spring: 25.3 ◼Shallowest well depth nearby: ⚫14 ft nearby ⚫13 ft in Central Ukiah ⚫~433 wells in 3-mile radius 13 less than 15 ft (3%) 58 less than 20 ft (13%) •Spring Meas. •23 ft-bgsMT •2015 Spring Meas. •20 ft-bgsMO DRAFT Central Ukiah Valley -15N12W08L001M (Aquifer II) ◼Average: ⚫Average fall: 25 ⚫Average spring: 19 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Fall: 26.3-30.1 (2014-15) ⚫Fall drop from average: ~5 ⚫Lowest Spring: 19.3-25.3 (2012-13) ⚫Spring drop from average: ~6 ⚫Largest Seasonal Change: 9.8 ◼Historical Min: ⚫Fall: 30.1 ⚫Spring: 25.3 ◼Shallowest well depth nearby: ⚫14 ft nearby ⚫13 ft in Central Ukiah ⚫~433 wells in 3-mile radius 13 less than 15 ft (3%) 58 less than 20 ft (13%) •Spring Meas. •23 ft-bgsMT •2015 Spring Meas. •20 ft-bgsMO DRAFT Southern Ukiah Valley -15N12W34Q001M (Aquifer I) ◼Average: ⚫Average fall: 33 ⚫Average spring: 19 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Falls: 35.3 -36 (2013-14) ⚫Fall drop from average: ~2 ⚫Lowest Spring: 28.5-32 (2013-14) ⚫Spring drop from average: ~13 ⚫Largest Seasonal Change: 21 ◼Historical Min: ⚫Fall: 37.2 ⚫Spring: 35.1 ◼Shallowest well depth nearby: ⚫35 ft nearby ⚫8 ft in Southern Ukiah ⚫~230 wells in 3-mile radius 79 less than 30 ft (34%) 38 less than 24 ft (17%) 14 less than 19 ft (6%) •Spring Meas. •30 ft-bgsMT •2015 Spring Meas. •24 ft-bgsMO DRAFT Southern Ukiah Valley -15N12W34Q001M (Aquifer I) ◼Average: ⚫Average fall: 33 ⚫Average spring: 19 ◼Multi-year drought: ⚫2012-2016 ⚫Lowest Falls: 35.3 -36 (2013-14) ⚫Fall drop from average: ~2 ⚫Lowest Spring: 28.5-32 (2013-14) ⚫Spring drop from average: ~13 ⚫Largest Seasonal Change: 21 ◼Historical Min: ⚫Fall: 37.2 ⚫Spring: 35.1 ◼Shallowest well depth nearby: ⚫35 ft nearby ⚫8 ft in Southern Ukiah ⚫~230 wells in 3-mile radius 79 less than 30 ft (34%) 38 less than 24 ft (17%) 14 less than 19 ft (6%) •Spring Meas. •30 ft-bgsMT •2015 Spring Meas. •24 ft-bgsMO DRAFTChronic Lowering of Groundwater Level Undesirable Result ◼Recommendations to improve the proposed possible SMC ◼Remember that the MT definition practically excludes all the CASGEM wells except DWR wells ~ Data gaps in Ukiah ◼This is the initial SMC set. Next steps: ⚫Use model and contour maps to model the impacts of such MTs and MOs on nearby wells and uses ⚫Check what these levels will translate into for SW depletion criteria, aquifer storage, and GDEs ⚫Bring back results for discussion in the TAC to revise the SMCs accordingly ⚫Iterate! DRAFT Thank you! Questions?