1. Slide 1 February 21, 2006 Oakdale Irrigation District Water Resources Plan A Community Plan. A Successful Future. Water Supply Reliability Oakdale Irrigation District Water Resources Plan A Community Plan. A Successful Future. Water Supply Reliability

2. 2 The Water Resources Plan Goals Technical Analyses Institutional Activities Public Involvement Provide long-term protection to OID’s water rights. Address federal, state, and local water challenges. Rebuild/modernize an out-of-date system to meet changing customer needs. Develop affordable ways to finance improvements. Involve the public in the planning process.

3. 3 The Project Team will need Board Input Throughout the PEIR Preparation Technical Analyses Institutional Activities Public Involvement Numerous issues from Phase 1 need continued Board input. Some items specifically relate to PEIR activities Other items, while not strictly tied to PEIR, need continued Board discussion

4. 4 Schedule of Board Involvement Water Supply Reliability and prelude to Transfer/Annexation issues (Informational Presentation)

5. 5 What is Water Supply Reliability and Why is it Important? w “Reliability” can mean different things to different people, for example: – To all users of Stanislaus River Supplies – Reliability of Stan. River supply to OID – Reliability of OID supplies to an OID customer w Typically expressed as a % w Reliability drives OID’s ability to annex new lands and/or transfer water.

6. 6 Oakdale ID Water Supply (2004 Usage) Stanislaus Pre-1914 Water – 257 TAF (93%) Stanislaus Post- 1914 Water – 1.3 TAF (>1%) Groundwater – 4.4 TAF (2%) Drainwater Reuse 13.5 TAF (5%)

7. 7 Stanislaus River Supplies to OID are Reliable – But not 100% Reliable w New Melones Reservoir constructed 1973 - 1983 w 1988 Agreement and Stipulation with Reclamation – OID and SSJID share the first 600 TAF of inflow w If inflow < 600 TAF, Districts share curtailments based on a formula (600 – Inflow divided by 3) w “Conserved water” up to 200 TAF but first spilled

8. 8 Computer Models are Used to Simulate Operations and Runoff

9. 9 Oakdale ID Receives its Full Allocation in 61 out of 77 Years 6 1 9 4 9 1 9 5 2 1 9 5 5 1 9 5 8 1 9 6 1 1 9 6 4 1 9 6 7 1 9 7 0 1 9 7 3 1 9 7 6 1 9 7 9 1 9 8 2 1 9 8 5 1 9 8 8 1 9 9 1 1 9 9 4 1 9 9 7 TA F

10. 10 6 1 9 4 9 1 9 5 2 1 9 5 5 1 9 5 8 1 9 6 1 1 9 6 4 1 9 6 7 1 9 7 0 1 9 7 3 1 9 7 6 1 9 7 9 1 9 8 2 1 9 8 5 1 9 8 8 1 9 9 1 1 9 9 4 1 9 9 7 TA F 1928 - 1934 246 – 300 TAF 1987 - 1992 230 – 300 TAF 1977 190 TAF

11. Statistics Help Summarize Stan R. Reliability–Independent of Acres Irrigated

12. Overlaying Current Customer Demand Tells More of the Story 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% The expected range of OID Stanislaus River demand not including current water transfer obligations is 262 to 299 TAF.

13. Overlaying Current Customer Demand Tells More of the Story 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% Without transfers, OID would need to augment Stanislaus River supply with additional sources under average ET conditions 9% of the time. The expected range of OID Stanislaus River demand not including current water transfer obligations is 262 to 299 TAF.

14. Overlaying Current Customer Demand Tells More of the Story 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% Without transfers, OID would need to augment Stanislaus River supply with additional sources under average ET conditions 9% of the time. Without transfers, OID would need to augment Stanislaus River supplies under maximum ET conditions 21% of the time. The expected range of OID Stanislaus River demand not including current water transfer obligations is 262 to 299 TAF.

15. 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% TAF The expected range of OID Stanislaus River demand including minimum water transfer obligations is 292 to 329 TAF. Overlaying all Current OID Demand for Stan. R. Water Tells the Whole Story

16. 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% TAF With minimum transfer obligations and average ET conditions, OID would need to augment Stanislaus supplies 19% of the time. The expected range of OID Stanislaus River demand including minimum water transfer obligations is 292 to 329 TAF. Overlaying all Current OID Demand for Stan. R. Water Tells the Whole Story

17. 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% TAF With minimum transfer obligations and average ET conditions, OID would need to augment Stanislaus supplies 19% of the time. The expected range of OID Stanislaus River demand including minimum water transfer obligations is 292 to 329 TAF. With minimum transfer obligations and maximum ET conditions, OID would need to augment their Stanislaus River supplies with other sources in every year. Overlaying all Current OID Demand for Stan. R. Water Tells the Whole Story

18. TAF 0 50 100 150 200 250 300 350 0%10%20%30%40%50%60%70%80%90%100% The expected range of OID Stanislaus River demand including minimum water transfer obligations is 312 to 349 TAF. What if OID Annexed 5,000 Acres Today (under current policies)?

19. 19 Conclusions (Current Land Use and Minimum Transfer Obligations) w In a maximum crop demand conditions, OID would need to augment its surface water supplies – Additional GW Pumping ($$ impact) – Reduced deliveries (modified rotations) w With average demand, OID would need to augment its surface water supplies 19% of the time

20. 20 The Water Resources Plan Recommends Improving Current Level of Reliability w Developed conservative plan to meet worst case needs. w “Worst case” is defined as a maximum water demand condition occurring simultaneous to an extreme (5% chance of occurrence) Stanislaus River Curtailment w Strategy dependent on upcoming OID policy decisions regarding drought response, annexation, and water transfers

21. 21 Implementing the WRP Improves Existing Customer Reliability w From an in-District grower perspective, assuming the following: – Max ET (299 TAF) – 30 TAF minimum transfer obligation – No annexations – 15 TAF of emergency pumping capability – Reduced rotations resulting in 10-14TAF in delivery curtailments w Customer reliability is 79% Current Customer Reliability

22. 22 Implementing the WRP Improves Existing Customer Reliability w From an in-District growers perspective, same assumptions, plus: – 5000 acres of annexations (current policies) w Maximum demand could be as high as 360 TAF (299+41+20). w With current facilities, this demand exceeds OID’s supplies Current Customer Reliability

23. 23 Implementing the WRP Improves Existing Customer Reliability w From an in-District growers perspective, assuming the following: – 2025 Demands (233 – 265 TAF) – 50 TAF Minimum transfer obligation – Over 4,000 acres of annexations – 20 TAF of emergency pumping capability and increased drainwater reuse – Reduced rotations resulting in 10-14TAF in delivery curtailments w Customer reliability is 95 to 99% Future Customer Reliability with WRP

24. 24 OID Can’t Improve Stanislaus River Reliability, Just Customer Reliability w Customer Reliability is also affected by board policies, facilities (gw and reuse), and land use w The WRP is structured to be implemented over time w Reliability improves steadily over the course of implementation w Additional water transfers and annexations need to be carefully phased – Availability of water supply – Financing of the WRP

25. 25 Schedule of Board Involvement CEQA Scoping Meeting

26. 26 Schedule of Board Involvement Expansion of Service Issues (Informational Presentation) and development of Annexation Policy Guiding Principles (Board Action)

27. 27 Schedule of Board Involvement Water Resources Planning Committee Discussion of Annexation Policy Guiding Principles

28. 28 Schedule of Board Involvement Annexation Policy Guiding Principles Board (Board Action) and Drought Response Plan (Informational Presentation)

29. 29 Schedule of Board Involvement 1)Water Transfer Discussion to include Extension of Existing Contracts, and Potential New Recipients. 2)Confirmation of “Preferred Alternative”. 3)Infrastructure Projects and Details (Informational Presentations)

30. 30 Implementing Best Apparent Alternative Will Benefit OID’s Customers and the Community w Protect OID’s water rights. w Enhance customer service for all users. w Rebuild, modernize, and expand system infrastructure. w Protect the future water supply needs of the cities of Oakdale and Riverbank. w Keep water rates affordable through a balanced effort of water transfers and service to “new” customers within OID’s Sphere of Influence. w Substantially increase water supply reliability and meet OID service in a worst-case drought.

31. Slide 31 February 21, 2006 Oakdale Irrigation District Water Resources Plan A Community Plan. A Successful Future. Water Supply Reliability Oakdale Irrigation District Water Resources Plan A Community Plan. A Successful Future. Water Supply Reliability