1. Northern Sacramento Valley Conjunctive Water Management Investigation The Glenn-Colusa Irrigation District and The Natural Heritage Institute October 21, 2010 10/21/20101

2. Today’s Workshop Objectives Provide a status report on the investigation progress Provide a status report on the investigation progress Listen/Respond to stakeholder questions Listen/Respond to stakeholder questions Describe next steps to investigation, public meetings, and final report Describe next steps to investigation, public meetings, and final report 10/21/20102

3. Motivating Factors - Regulatory and Legislative Changes Significant Values are at Risk: Regional Sustainability Significant Values are at Risk: Regional Sustainability Environmental Environmental Water supply Water supply Economy Economy New Challenges New Challenges SWRCB Flow Report: 75% unimpaired flow to the Delta November-June SWRCB Flow Report: 75% unimpaired flow to the Delta November-June DFG Report confirms similar flow needs DFG Report confirms similar flow needs Delta species (smelt) dominate, salmon at risk Delta species (smelt) dominate, salmon at risk Delta Stewardship Council: All Delta all the time Delta Stewardship Council: All Delta all the time Scott Valley/Siskiyou County Groundwater Pumping Lawsuit Scott Valley/Siskiyou County Groundwater Pumping Lawsuit The Past is the past, How do we control our destiny? The Past is the past, How do we control our destiny? Historical operations and uses are constantly changing Historical operations and uses are constantly changing Local needs and flexibility are now challenged in the Delta context Local needs and flexibility are now challenged in the Delta context Increasing costs and fees Increasing costs and fees Long term stability and reliability? Long term stability and reliability? 10/21/20103

4. Emerging Values What does the region want, what values should be protected? What does the region want, what values should be protected? Water supply reliability (surface/groundwater)? Water supply reliability (surface/groundwater)? Environmental protection/enhancement, both instream and terrestrial? Environmental protection/enhancement, both instream and terrestrial? System sustainability, what is it? System sustainability, what is it? Others…? Others…? What strategies should be pursued to achieve regional goals? What strategies should be pursued to achieve regional goals? Status quo? Status quo? Regional water investigations and planning? Regional water investigations and planning? Others…? Others…? Just say no…will that do? Just say no…will that do? 10/21/20104

5. Overview of Investigation to Date 10/21/20105

6. 6 Program Objective Examine whether and how operation of groundwater aquifers in the Sacramento Valley could be integrated with operation of existing surface water reservoirs to produce additional firm water supplies Examine whether and how operation of groundwater aquifers in the Sacramento Valley could be integrated with operation of existing surface water reservoirs to produce additional firm water supplies Potential benefits: Potential benefits: Improved water supply reliability (local, regional, State) Improved water supply reliability (local, regional, State) Ecosystem restoration (Sacramento and Feather Rivers) Ecosystem restoration (Sacramento and Feather Rivers) Improved Delta inflow per BDCP Improved Delta inflow per BDCP Increased operational flexibility (CVP, SWP, local) Increased operational flexibility (CVP, SWP, local) Buffer effects of climate change Buffer effects of climate change 10/21/20106

7. Program Requirements New net benefits for Sacramento Valley environment and water users New net benefits for Sacramento Valley environment and water users CVP and SWP commitments honored (to the extent they presently are) CVP and SWP commitments honored (to the extent they presently are) No unmitigated impacts to existing groundwater users No unmitigated impacts to existing groundwater users Economic feasibility Economic feasibility 10/21/20107

8. 8 Initial Site Screening What Makes for an Attractive Water Banking Site? Groundwater conditions Groundwater conditions Available aquifer storage space Available aquifer storage space Viable recharge mechanism Viable recharge mechanism Productive groundwater wells Productive groundwater wells Suitable GW quality Suitable GW quality Surface water conditions Surface water conditions Surplus flows at times Surplus flows at times Connection to CVP, SWP or other surface water reservoirs Connection to CVP, SWP or other surface water reservoirs Dual SW and GW use option Dual SW and GW use option Impacts/mitigation Impacts/mitigation Isolation from important surface streams Isolation from important surface streams Isolation from existing groundwater production wells Isolation from existing groundwater production wells Ability to mitigate or compensate impacts that cannot be avoided Ability to mitigate or compensate impacts that cannot be avoided 10/21/2010

9. 9 Typical Sacramento Valley GW Hydrograph (Butte Co.) Early Finding: Traditional water banking generally not viable in the Sacramento Valley due to lack of aquifer storage space. 10/21/2010

10. 10 Re-operate Surface Reservoirs with Groundwater “Backstop” Reservoir re-operation Reservoir re-operation Additional releases to meet program objectives Additional releases to meet program objectives Hope for reservoir refill from surplus surface flows Hope for reservoir refill from surplus surface flows Honor existing CVP and SWP delivery obligations and operations constraints Honor existing CVP and SWP delivery obligations and operations constraints Groundwater operation Groundwater operation Pump groundwater to “repay” reservoirs if storage conditions put contract deliveries or temperature control at risk Pump groundwater to “repay” reservoirs if storage conditions put contract deliveries or temperature control at risk Groundwater used in lieu of surface entitlements that then remain in storage Groundwater used in lieu of surface entitlements that then remain in storage 10/21/2010

11. 11 Three Sites Identified Glenn-Colusa ID connected to CVP/Shasta Butte Basin connected to SWP/Oroville Orland Unit connected to Stony Creek Reservoirs 10/21/2010

12. 12 Glenn-Colusa ID connected to CVP/Shasta Butte Basin connected to SWP/Oroville Two Sites Selected for Modeling 10/21/2010

13. Re-operation Conceptual Example Release water from CVP and/or SWP reservoirs to meet project objectives: Release water from CVP and/or SWP reservoirs to meet project objectives: Unmet local ag demands Unmet local ag demands Regional environmental flow targets Regional environmental flow targets If reservoirs refill, no subsequent GW pumping is needed If reservoirs refill, no subsequent GW pumping is needed If reservoirs do not refill, pump GW and forego use of surface water in following year as needed for reservoir “payback” If reservoirs do not refill, pump GW and forego use of surface water in following year as needed for reservoir “payback” New SW supplies can be generated with infrequent additional GW pumping, because reservoirs refill most years New SW supplies can be generated with infrequent additional GW pumping, because reservoirs refill most years 10/21/201013

14. 14 Project Scenarios Defined by Groundwater Pumping Capacity and Season Scenario Groundwater Pumping Capacity (thousand acre-feet) Pumping Season GCID(CVP) Butte Basin (SWP)Total 110050150summer 2200100300summer 310050150fall 410050150 summer & fall All scenarios modeled with an existing (shallow) and new (deep) well field to reveal range of potential impacts to streams and existing pumpers. 10/21/2010

15. 15 Surface Water Model Results (Example for Scenario 1, Shasta/CVP, 100 TAF Pumping Capacity in GCID) Environmental flow releases Environmental flow releases Agricultural deliveries Agricultural deliveries Refill from surplus surface water Refill from surplus surface water Refill from groundwater pumping Refill from groundwater pumping 10/21/2010

16. 16 Environmental Flow Objectives Geomorphic Geomorphic Single day large event Single day large event February or March February or March Riparian establishment Riparian establishment Five day large flow with 60 day recession Five day large flow with 60 day recession April start April start Flood plain inundation Flood plain inundation Single day large event with 45 day recession Single day large event with 45 day recession Between February and April Between February and April Spring pulse flow Spring pulse flow Simulate more natural spring runoff period Simulate more natural spring runoff period 10/21/2010

17. 17 Scenario 1—CVP/Shasta 100 TAF Pumping Capacity in GCID Environmental Flow Releases 10/21/2010

18. 18 Scenario 1—CVP/Shasta 100 TAF Pumping Capacity in GCID Sac River Agricultural Deliveries 10/21/2010

19. 19 Scenario 1—CVP/Shasta 100 TAF Pumping Capacity in GCID Refill from Surplus Surface Water 10/21/2010

20. 20 Scenario 1—CVP/Shasta 100 TAF Pumping Capacity in GCID Refill from Groundwater Pumping 10/21/2010

21. 21 SW Modeling Summary (Annual averages 1922-2003, taf) Scenario CVP/Sacramento River SWP/Feather River Env.Rel. Ag. Del. Refill from SW GW Pump Env.Rel. Ag. Del. Refill from SW GW Pump 1,3 and 4 1314243710143 245225892320367 10/21/2010

22. 22 SW Modeling Summary (Average in years of occurrence 1922-2003, taf) Scenario CVP/Sacramento River SWP/Feather River Env.Rel. Ag. Del. Refill from SW GW Pump Env.Rel. Ag. Del. Refill from SW GW Pump 1,3 and 4 9446707049273244 21877513912395527275 10/21/2010

23. Project Impacts Due to Additional Groundwater Pumping Streamflow Streamflow Butte Creek in affected area Butte Creek in affected area Other critical streams not in affected areas Other critical streams not in affected areas Ephemeral streams not analyzed Ephemeral streams not analyzed Groundwater levels and existing wells Groundwater levels and existing wells Well yield impacts Well yield impacts Incremental pumping costs (due to additional lift) Incremental pumping costs (due to additional lift) 2310/21/2010

24. Butte Creek Impacts 24 Develop baseline flow from available gauging stations Develop baseline flow from available gauging stations Synthesize “with-project” flows based on cumulative reductions in streamflow from changes in stream leakance from GW model Synthesize “with-project” flows based on cumulative reductions in streamflow from changes in stream leakance from GW model 10/21/2010

25. Butte Creek Impacts No impact in upper reaches (primary spawning and holding areas) No impact in upper reaches (primary spawning and holding areas) Greatest flow reduction in Jan. – Mar. Greatest flow reduction in Jan. – Mar. During times of highest discharge During times of highest discharge Greatest % reduction in summer/early fall Greatest % reduction in summer/early fall Spring-run have already migrated Spring-run have already migrated Steelhead just beginning to enter stream Steelhead just beginning to enter stream Rarely drops below in-stream standards Rarely drops below in-stream standards June during early ‘90s drought June during early ‘90s drought Tradeoffs between Butte Creek impacts and main stem benefits Tradeoffs between Butte Creek impacts and main stem benefits 2510/21/2010

26. Impacts to Existing Wells Used DWR well inventory data Used DWR well inventory data No appreciable impact on irrigation well performance No appreciable impact on irrigation well performance Increased pumping costs accounted for Increased pumping costs accounted for Some impact on non-irrigation wells Some impact on non-irrigation wells 9,000 non-irrigation wells in analysis area 9,000 non-irrigation wells in analysis area Up to ~800 non-irrigation wells in impact zones Up to ~800 non-irrigation wells in impact zones Maximum of 25 (0.2%) to 284 (3%) of wells needing deepening or replacement Maximum of 25 (0.2%) to 284 (3%) of wells needing deepening or replacement 10/21/201026

27. 27 Potential Impact Zones: Worst Case, New Wells Groundwater Levels and Impacts to Wells Potential Impact Zones: Worst Case, Existing Wells

28. Incremental Pumping Costs 28 Summary Statistics of Interference Drawdown by Pumping Scenario 10/21/2010

29. Incremental Pumping Costs 29 Summary Statistics of Total Increased Annual Energy Costs to Maintain Existing Groundwater Pumping for Irrigation. (Incremental costs for non-irrigation pumping on the order of $3000 - $5000 per year depending on pumping scenario) 10/21/2010

30. Benefit-Cost Summary 30 All present values in million dollars [2009] Scenario BenefitsCosts Benefit – Cost No.Description 1150 TAF Summer, New Wells73135-62 1150 TAF Summer, Existing Wells7394-21 2300TAF Summer, New Wells183290-107 2300 TAF Summer, Existing Wells183212-29 3150 TAF Fall, New Wells74210-136 3150 TAF Fall, Existing Wells74144-70 4150 TAF Summer & Fall, New Wells7388-15 4150 TAF Summer & Fall, Existing Wells73658 10/21/2010

31. Latest Activities and Findings 10/21/201031

32. Exploring Operations for Additional Environmental Benefits Consultation with CVP and SWP operators Consultation with CVP and SWP operators Complying with temperature requirements of greatest concern Complying with temperature requirements of greatest concern Operators provided “unofficial” operations criteria for modeling Operators provided “unofficial” operations criteria for modeling Operating for temperature benefit involves tradeoffs with project environmental flow objectives Operating for temperature benefit involves tradeoffs with project environmental flow objectives 10/21/201032

33. Temporary Crop Idling to Reduce Payback Cost Investigated crop idling as an alternative to GW pumping for reservoir payback Investigated crop idling as an alternative to GW pumping for reservoir payback Voluntary, incentive driven Voluntary, incentive driven Less cost-effective than pumping due to: Less cost-effective than pumping due to: High cost: crop idling decisions have to be made early before hydrologic conditions are known High cost: crop idling decisions have to be made early before hydrologic conditions are known Marginal effectiveness: not all of the avoided water use results in reservoir payback Marginal effectiveness: not all of the avoided water use results in reservoir payback 10/21/201033

34. Principal Findings to Date SWP and CVP operational requirements are complex and constraining SWP and CVP operational requirements are complex and constraining Must honor all Project commitments and operations rules Must honor all Project commitments and operations rules Cold water pool management has dominant effect Cold water pool management has dominant effect Cost of payback water is appreciable Cost of payback water is appreciable Groundwater pumping Groundwater pumping Temporary crop idling Temporary crop idling Project cost-effectiveness is marginal Project cost-effectiveness is marginal Use of Sac groundwater to “backstop” entails mitigation costs Use of Sac groundwater to “backstop” entails mitigation costs Project water produced in wetter years because it cannot be banked Project water produced in wetter years because it cannot be banked Modest value of water in Sac Valley Modest value of water in Sac Valley 10/21/201034

35. Concluding Phase 1 10/21/201035

36. Final Phase 1 Steps Technical Technical Frame existing operational constraints and tradeoffs Frame existing operational constraints and tradeoffs Formulate and model best performing scenario under existing conditions Formulate and model best performing scenario under existing conditions Analyze impacts and economics Analyze impacts and economics Final Report: draft, final Final Report: draft, final Public meetings (between draft and final) Public meetings (between draft and final) Scope Phase 2 of Investigation Scope Phase 2 of Investigation Continue regional dialogue Continue regional dialogue 10/21/201036

37. Question & Answer Discussion