Greater Kaweah GSA Technical Advisory Committee Meeting - PDF document

7/2/2019 Greater Kaweah GSA Technical Advisory Committee Meeting www.GreaterKaweahGSA.org Tuesday, July 2, 2019 ITEM 2: ANNOUNCEMENTS 1

7/2/2019 2

7/2/2019 ITEM 3: MINUTES ITEM 4: UPDATE ON SUSTAINABLE MANAGEMENT CRITERIA DEVELOPMENT 3

7/2/2019 Subsidence Sustainable Management Criteria • Annual Rate* • Areal Extent* * That substantially interferes with land uses and may lead to undesirable results. Subsidence Approach to SMCs Subsidence correlates to change in groundwater storage • Project observed groundwater levels (Fall 2006 to 2016) to 2040 • due to maximum withdrawal of groundwater Estimate volume of groundwater storage due to maximum • withdrawal – 4,000,000 acre-feet Estimate potential subsidence, based on actual subsidence • during 5-year drought 4

7/2/2019 Subsidence versus Groundwater Storage Correlation period Not effected by differences in water years ** Stable or slight rebound during above-normal water years ** Subsidence during below-normal water years* * 87 inches of additional subsidence could result from removal of 4M AF of groundwater storage Subsidence Minimum Threshold • Interpolated between GPS Stations CRCN and P566 87 inches versus 10 inches (2017 to 2040) • Projected NW and SE to KDWCD station • 3.4 inches/year red shading • 0.5 inches/year blue shading 5

7/2/2019 Water Quality Trends • GAMMA database extraction for GKGSA area o Arsenic o Nitrate o Total Dissolved Solids (TDS) Time # of Constituent Period Results Detects Muni Dom Mon Unk Arsenic, ug/l 1968 – 2019 1,081 63% 91% 4% 2% 3% Nitrate, mg/l as N 1945 – 2019 3,917 96% 88% 1% 2% 9% TDS, mg/l 1945 - 2019 841 100% 67% 5% 3% 26% Arsenic Trend Median Values • Significantly greater sampling during 2000s and 2010s • Limited data before 2000, variable results, high reporting limits • Relatively stable trend 1990s to 2010s • Percent samples exceeding primary MCL of 10 ug/l 1990s: 31% o 2000s: 23% o 2010s: 23% o 6

7/2/2019 Nitrate Trend Median Values • Significantly greater sampling during 2000s and 2010s • Limited data before 1990, variable results • Steady increasing trend 1940s to 2010s • Percent samples exceeding primary MCL of 10 mg/l as N 1990s: 1% o 2000s: 15% o 2010s: 28% o TDS Trend Median Values • Fair amount of sampling during 1970s through 1990s • Significantly greater sampling during 2000s and 2010s • Slight decreasing trend 1940s to 2010s • Percent samples exceeding secondary MCL of 1000 mg/l 1990s: 0% o 2000s: 5% o 2010s: 11% — Deep groundwater?? o 7

7/2/2019 Sustainability Goal and Undesirable Results: Groundwater Quality Options for GSA Participation in Water Quality Improvement Programs 1. Provide Education and Information – Groundwater Basin Conditions – Funding Opportunities – Remediation/Treatment Technologies 2. Active GSA Coordination with Water Quality Agencies and Coalitions – Participate in meetings (salinity prioritization & optimization study, management zones) as a contributor of information, but also seeking information – Exchange/Share GW quality data and information between GSAs and other GWQ leads. – Request information to better inform 5-year GSP updates, include data in DMS as it becomes publicly available 3. Identify, Pursue, Administer Grants in Partnership with Water Quality Agencies ITEM 5: UPDATE ON PROJECTS AND MANAGEMENT ACTIONS DEVELOPMENT 8

7/2/2019 Initial GW Model Runs 2) Future No Project Scenario: Base Case – Assumes current water budget conditions exist in the future modified only by DWR provided climate data sets and forecasts of supply and demand. Distribution of groundwater pumping is consistent with current water budget period – GW model forecasts future groundwater levels for comparison against minimum thresholds Initial GW Model Runs 3) Future Management Actions Only: Pumping Reductions – Assumes current water budget conditions exist in the future modified only by DWR provided climate data sets and forecasts of supply and demand and pumping conforms to water allocations in water accounting framework – GW model forecasts future groundwater levels for setting groundwater level measurable objective and interim milestones 9

7/2/2019 Initial GW Model Runs 4) Future Management Actions Only: Pumping Reductions + Projects – Assumes current water budget conditions exist in the future modified only by DWR provided climate data sets and forecasts of supply and demand, pumping conforms to water allocations in water accounting framework, and projects area implemented on planned schedule. – GW model forecasts future groundwater levels for setting groundwater level optimal measurable objective and interim milestones  Focused on modeling projects that are currently under construction or that are eminent  Conceptual projects will be described in the GSP but will not be taken credit for initially 4. Projects and Management Actions Greater Kaweah:  GKGSA’s Target (1997-2017 Water Budget Apportioned to WAF) = 42,675 acre-feet/year  Annual Native Yield of the Basin and GKGSA = 363,784 acre-feet or 0.82 acre-feet/acre/year  GKGSA’s share of net subsurface inflow from adjacent subbasins = 32,250 acre-feet/year Possible Projects and/or Management Actions Alternatives Alternatives Apportionment of Average Annual Net Targets as a Percentage of Average Annual Sustainable Increase in Supply Minus Subsurface Inflow & Yield Deficit (overdraft + half of basin subsurface inflow) Reduction in Demand in Average Annual Acre-Feet Alt. 2020-25 2026-30 2031-35 2036-40 Total Alt. 2020-25 2026-30 2031-35 2036-40 Total 1 0% 20% 35% 45% 100% 1 1 0 14,985 26,224 33,716 2 5% 25% 30% 40% 100% 2 2 3,746 18,731 22,478 29,970 Goal 3 5% 20% 35% 40% 100% 3 3 3,746 14,985 26,224 29,970 Optimal 4 10% 20% 30% 40% 100% 4 4 7,493 14,985 22,478 29,970 5 10% 30% 30% 30% 100% 5 5 7,493 22,478 22,478 22,478 6 25% 25% 25% 25% 100% 6 6 18,731 18,731 18,731 18,731 Average Annual Project & MA Targets and Goal/Optimal Goal Differences for Interim Periods (acre-feet) 2020-25 2026-30 2031-35 2036-40 Targets 24,975 33,577 70,769 83,615 Goal Diff 21,229 14,846 25,814 8,690 Opt Diff 17,482 11,099 25,814 8,690 10

7/2/2019 3. Projects and Management Actions Greater Kaweah: Annual Project & MA Targets For Input To The Model (Acre-Feet) Water Year Projects Specific MAs Undefined MAs Annual Total Running Total 2020 9,400 0 0 9,400 9,400 2021 9,700 4,500 750 14,950 24,350 2022 9,700 4,000 1,000 14,700 39,050 2023 69,400 8,000 1,250 78,650 117,700 2024 10,200 4,000 1,500 15,700 133,400 2025 10,200 4,500 1,750 16,450 149,850 2026 10,200 4,000 3,857 18,057 167,907 2027 83,000 8,000 3,857 94,857 262,764 2028 10,300 4,000 3,857 18,157 280,921 2029 10,300 4,500 3,857 18,657 299,578 2030 10,300 4,000 3,857 18,157 317,735 2031 94,100 8,000 19,149 121,249 438,984 2032 10,500 4,000 19,149 33,649 472,633 2033 10,500 4,500 19,149 34,149 506,782 2034 10,500 4,000 19,149 33,649 540,431 2035 104,000 8,000 19,149 131,149 671,580 2036 10,600 4,000 48,715 63,315 734,895 2037 10,600 4,500 48,715 63,815 798,710 2038 10,600 4,000 48,715 63,315 862,025 2039 107,600 8,000 48,715 164,315 1,026,340 2040 10,600 4,000 48,715 63,315 1,089,655 Preliminary Projects & Management Actions Model Run Results MT 11

7/2/2019 Preliminary Projects & Management Actions Model Run Results MT Preliminary Projects & Management Actions Model Run Results MT 12

7/2/2019 ITEM 6: TECH SERVICES UPDATE ITEM 6: Technical Services Update Summary of Kaweah Coordination • Subbasin Basin Setting Components Report – Completed incorporation of clean up comments • Numerical Model – GSI completed Base Run Scenarios – GSI completed initial run of scenarios with Projects and Management Actions • Draft Coordination Agreement discussions are ongoing. • Completion of SkyTEM study 13

7/2/2019 ITEM 6: Technical Services Update Summary of Kaweah Coordination • DMS funds from GSP grant to be reallocated to Basin contract • Recent Management Team Committee meeting agenda included: – Groundwater Quality suggested approach by GEI, and CV-SALTS presentation by Richard Meyerhoff (GEI) – Preliminary modeling results – DMS update and walk-through – Prop 68 funding discussion ITEM 6: Technical Services Update Kaweah Data Management System (DMS) Objective: Develop a coordinated data storage, analysis, visualization, and reporting tool for groundwater-related information within the entire Kaweah Sub-Basin Key Features: 1) Store and display information from previous, ongoing, and future groundwater studies and monitoring programs 2) Protect against the loss of invaluable data 3) Facilitate direct production of tables, charts, maps, and graphs 14