Greater Kaweah GSA Technical Advisory Committee Meeting - PDF document

5/6/2019 Greater Kaweah GSA Technical Advisory Committee Meeting www.GreaterKaweahGSA.org Monday, May 6, 2019 ITEM 2: ANNOUNCEMENTS 1

5/6/2019 ITEM 3: MINUTES ITEM 4: UPDATE ON DRAFT GSP MONITORING NETWORK CHAPTER 2

5/6/2019 ITEM 5: UPDATE ON SUSTAINABLE MANAGEMENT CRITERIA DEVELOPMENT SMCs Approach for Groundwater Levels • For each Representative Monitoring Site, the Minimum Threshold for Groundwater Levels would be established at the projected 2040 GWL. – This approach is meant to account for a “worst-case scenario” in which we experience worse drought conditions than we have historically. • The Measurable Objective for Groundwater Levels would be the projected 2030 GWL. – Provides 10 years of drought storage in the “worst-case scenario”. 3

5/6/2019 4

5/6/2019 5

5/6/2019 6

5/6/2019 SMCs for Change in Storage • The change in groundwater storage is correlated to the chronic decline in groundwater levels. Therefore, the SMCs for groundwater levels will be used as a proxy for the change in storage. SMCs for Water Quality • The Basin Setting has identified existing water quality issues. However, undesirable results related directly to groundwater levels have not been observed to-date. • To re-evaluate a Minimum Threshold and Measurable Objective for each of the Constituents of Concern discussed in the Basin Setting, ongoing and future water quality monitoring will coincide with GWL measurements. – e.g. The Kaweah Watershed Coalition has begun to collect water quality samples coincidental with GWL measurements. 7

5/6/2019 SMCs for Water Quality • In addition to the IRLP, there are other existing programs (i.e. Title 22 Drinking Water Program) which monitor water quality and will be used to determine the occurrence of an Undesirable Result, due to the migration of existing groundwater contamination. SMCs for Subsidence • The Basin Setting identifies Land Subsidence as a current condition in the subbasin. However, damage to critical infrastructure within the Kaweah Subbasin has not been observed to-date. • To establish an Minimum Threshold and Measurable Objective for subsidence, one method would use the change in storage (with respect to the SMCs for GWLs) to develop correlations between change in storage and rates of subsidence. • Another method would be to calculate the potential land subsidence, based on the change in storage, and set a land elevation for Minimum Thresholds and Measurable Objectives at the Representative Monitoring Sites. 8

5/6/2019 ITEM 6: Measurement & Monitoring Options Vendor Product Accuracy Pros Cons Unit Cost • • Rosemount 8750 Mag 0.25% - 0.5% Proven Record Cost ~ $5200/unit • • Meter Expandable Wireless Network Wireless network will be an Capabilities for Remote add’l cost Communication • • PowWow +/- 4% Inexpensive Yearly recurring payments $500/unit • • No Add’l Installation Cost No option to add GWL $200-$300/unit on • Bulk Discounts up to ~60% monitoring instruments to bulk orders • Maintains Title 23 Certification system (< 10% error) • • • McCrometer FPI Mag 0.5% - 1.0% Meter installed on Pump Cost ~$5500/unit • • Meter Multiple Meters can track flow Add’l installation cost • • Ultra Mag 0.5% to individual fields/crops May not fit for all Meter applications • Add’l cost for network • • McCrometer Propeller 2% Inexpensive, compared to mag Moving parts that can be ~$2,800/unit Meters meters damaged/become worn • Require longer pipe runs for installation • Add’l installation cost TSS Funding for Monitoring Wells • The Kaweah Subbasin was approved for TSS funding to provide additional, SGMA-compliant monitoring wells. – In February, the GSAs were notified that DWR was still working with its drilling contractor to develop the schedule and negotiating on the costs to be able to complete as many wells as possible in this first round of funding. – As of earlier this week, the draft language for the Agreement was provided to the GSAs for their review. – DWR will provide the Agreement documents, completed with information provided in the TSS application in the coming weeks. – DWR is also asking each basin to prioritize the order of wells to be drilled, in case there is not sufficient funding to complete all wells in the basin. 9

5/6/2019 ITEM 7: TECH SERVICES UPDATE Kaweah Subbasin Activities • Subbasin Basin Setting Components Report – Delivered to GSA Managers and discussed at Subbasin Management Team meeting on March 20 th . – Further discussion at the TAC meeting on April 26 th . GEI to respond to comments for May 6 th TAC meeting. • Numerical Model – Refined with water budget refinements, discussed at Management Team meeting. GSAs managers discussing which simulations to run in the model. • Draft Coordination Agreement discussions are ongoing. • Water Budget components have been applied to Water Supply Accounting Framework that has been agreed upon at the Subbasin-level. Currently under review with the GSA managers. 10

5/6/2019 Kaweah Subbasin Coordination (cont.) KSB Basin Setting Status • KSB Managers and GSA TAC recently completed review of December 1, 2019 Draft Basin Setting • Approved Amended Task Order KSB-05.2018 – Basin Setting at February Meeting • GEI Team has incorporate KSB Managers comments addressing these issues: 1. Decrease Kaweah River and CVP Water deliveries 2. Decrease Mountain Front Recharge in EKGSA and portions of GKGSA 3. Recalculate percolation or precipitation and applied water during period 1981-1999 using different methodology 4. Improve boundary flux estimates using numerical groundwater model 5. Document the specific yield method for calculating change in groundwater basin storage Kaweah Subbasin Coordination (cont.) Revised Water Budgets Each of these three water budgets periods have been refined with the recent Basin Setting Update • Historic Period – 1981 to 2017 • Current Period – 1997 to 2017 • Projected Future – 2017 to 2070 11

5/6/2019 Kaweah Subbasin Coordination (cont.) QC Checks on Water Budget Accounting Groundwater Modeling Specific Yield Analysis Historic Modeling Method Period Period Water Budget - 2,428,500 - 2,715,500 (Inventory) Specific Yield - 3,127,300 - 2,948,600 Numerical Model -- - 2,656,000 Kaweah Subbasin Coordination (cont.) Ave Overdraft – Historical vs. Current Historical Average Current Average Overdraft: 65,600 AF/Y Overdraft: 77,591 AF/Y 12

5/6/2019 Kaweah Subbasin Coordination (cont.) Projected Water Budget Water Supply Accounting Framework 13

5/6/2019 Native Water ( Segregated by GSA Acreage) Native Water East Greater Mid Total Perc of Precip (Ag and 'Native' non-Ag land) 23,666 44,213 20,974 88,854 Streambed Perc from Kaweah River Sources 16,767 31,324 14,860 62,952 Irrigation Ret. Flow from Pumped GW 41,484 77,501 36,766 155,752 Mountain Front Recharge 14,976 27,978 13,273 56,227 Total Native 96,894 181,017 85,874 363,784 GSA % of Total Native 27% 50% 24% Foreign Water ( Segregated by Appropriator) Foreign Water East Greater Mid Total Streambed Perc from Imported Sources 0 1,638 12,615 14,253 Ditch Perc from Imported Sources 0 1,204 21,745 22,949 Basin Perc from Imported Sources 0 1,050 14,305 15,355 Irrigation Ret. Flow from Imported Sources 12,073 1,241 7,140 20,453 Total Foreign 12,073 5,133 55,805 73,010 GSA % of Total Foreign 17% 7% 76% 14

5/6/2019 Salvaged Water (Segregated by Appropriator) Salvaged Water East Greater Mid Total Ditch Perc from Kaweah River Sources 8,835 49,771 34,880 93,486 Additional Recharge 226 6,892 5,697 12,815 Stormwater Return Flows 508 2,370 8,491 11,368 WWTP Return Flows 1,470 3,129 13,878 18,477 Basin Perc from Kaweah River Sources 0 16,005 23,479 39,484 Irrig. Ret. Flow from Kaweah River Sources 4,555 31,039 11,981 47,574 Total Salvaged 15,593 109,205 98,406 223,205 GSA % of Total Salvaged 7% 49% 44% Allocation Summary Allocation Bucket East Greater Mid Total Total Native 96,894 181,017 85,874 363,784 Total Foreign 12,073 5,133 55,805 73,010 Total Salvaged 15,593 109,205 98,406 223,205 Grand Total 124,560 295,355 240,084 659,999 GSA % of Total 19% 45% 36% 15

5/6/2019 Initial GW Model Runs 1) Water Allocation Verification – Purpose of this run is to verify and refine the water allocation results just presented derived from the inventory method water budget 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 16