Eduardo Garaña , P.E. Director-Water Department October 15, 2003

1. Lake Corpus Christi/Choke Canyon Water Rights Permit &Reservoir Operating Plan/Water Use Projections and Current Major Projects Eduardo Garaña , P.E. Director-Water Department October 15, 2003

2. Key Dates/Events • May 1976 - City of Corpus Christi applied for Choke Canyon Water Rights. • October 1976 - Texas Water Rights Commission issued Choke Canyon Water Rights Permit with freshwater inflow requirements. • June 1982 - Choke Canyon Dam construction completed. • May 1984 - Choke Canyon Water Right Permit adjudicated, • June 1987 - Choke Canyon filled and spilled the first time.

3. Key Dates/Events (Cont.) • December 1989 - Letter received by the TNRCC questioning freshwater inflows. • May 1990 - TNRCC ordered City to begin freshwater inflows to Bays and Estuaries. • March 1992 -TNRCC Agreed Order amended interim operational procedures and created NEAC. • April 1995 - TNRCC Agreed Order amends operational procedures and continues NEAC. • April 2001 - TNRCC Agreed Order amends operational procedures and continues NEAC.

4. Choke Canyon Water Rights Permit # 3358 Special Condition 5 (b): “Following completion and filling of Choke Canyon Dam and reservoir, scheduled releases shall be made from the reservoir system at Lake Corpus Christi Dam together with return flows to the estuaries for the proper ecological environment and health of related living resources therein. …”

5. Choke Canyon Water Rights Permit # 3358 Special Condition 5 (b)(cont): “...Water provided to the estuaries from the reservoir system under this paragraph shall be released in such quantities and in accordance with such operational procedures as may be ordered by the Commission. Permittees shall provide not less than 151,000 acre-feet of water per annum for the estuaries by a combination of releases and spills from the reservoir system at the Lake Corpus Christi Dam and return flows to Nueces and Corpus Christi Bays and other receiving estuaries.”

6. Certificate of Adjudication No. 21-3214, 1984 - Special Condition 5.b. • Special Condition 5.b: • Requires permit holders to provide freshwater inflows to the Nueces Estuary “for the proper ecological environment and health of related living marine resources therein.” • States that freshwater inflows shall: • Be not less than 151,000 acre-feet annually • Begin after Choke Canyon fills for the first time • Be in accordance with operational procedures as ordered by the Commission (now TNRCC) • Be a combination of spills, releases and return flows • Federal 404 Permit includes freshwater inflow requirement.

7. Creates NEAC Whose Mission is to “Consider Such Additional Information and Related Issues and to Formulate Recommendations for the Commission’s Review and Actions.” 1992 Agreed Order • Amended the 1990 Reservoir System Operational Procedures by Establishing a Monthly Schedule of Required Inflow Amounts. • 97,000 acft/yr. total to Nueces Bay • 500 acft/mo. return flow credits

8. 1995 Agreed Order • Limits amount of “releases” to amount of reservoir system inflows, up to a monthly estuary inflow target • Targets essentially the same as previous release schedule. • “Pass-through” reservoir inflows up to monthly target. • Reservoir inflows above monthly target are captured & stored. • If reservoir inflows are less than monthly target, only inflow amount is “passed through.” • No requirement to “release” stored water to make up the difference. • Monthly targets reduced when salinity is in desirable range. • Credits for excess pass-through’s in one month carried to next. • Drought contingency provisions drastically reduce targets during low flow periods.

9. 2001 Agreed Order • Diverts Pass-through’s and Other Inflows to Nueces Delta • Nueces River Overflow Channel into Rincon Bayou. • Pipeline from Calallen Pool to Rincon Bayou. • Provides for Automatic Measures and Relief • 50%: Increased Public Awareness. • 40%: Restrict Time-of-Day Lawn Watering. • (Inflow Targets Reduced to 1,200 af/mo) • 30%: Restrict Lawn Watering to No More Than Once Every 5 Days. • (Inflow Targets Suspended)

10. Agreed Order Summary • The City of Corpus Christi, as Operator of the Reservoir System, shall provide not less than 151, 000 ac-ft of water per annum for the estuaries >70% storage capacity—138,000 ac-ft target >40% but less than 70%--97,000 ac-ft target >30% but less than 40%-- 1,200 ac-ft target* <30%-- Total suspension of Pass-thrus* * Implementation of Lawn Watering Restrictions

11. Agreed Order Summary (cont.) • Additional Relief Options: >Flows in excess of monthly targets >Salinity levels in Upper Nueces Bay • Water Conservation and Drought Contingency Plans for Customers

12. Sources of Nueces River Basin Water Supply AUSTIN LEAKEY HOUSTON DEL RIO SAN ANTONIO Choke Canyon Dam Completed – 1982 UVALDE Frio River Atascosa River Frio River Basin EAGLE PASS Nueces River Nueces River Basin CORPUS CHRISTI Wesley Seale Dam Completed – 1958 LAREDO

13. Current Operating Policy • Revised during 1996-7 drought. • …..in order to provide maximum dependable yield from the two reservoirs, the water level in Lake Corpus Christi will be allowed to drop to elevation 74 feet before water is released from Choke Canyon Reservoir….. When the elevation of Choke Canyon Reservoir drops to 155 feet, Lake Corpus Christi will be lowered to its minimum elevation.

14. Beeville Pipeline 1982 Lake Corpus Christi Reservoir Wholesale Water Providers Mathis Pipeline 1982 Alice Pipeline 1964

15. Choke Canyon / Lake Corpus Christi Reservoir SystemDaily Pass-Through Status ReportReport Date: May 28, 2002 RESERVOIR STATISTICS

16. Weather Related Information

17. STREAM FLOWS

18. USGS Gauge Locations NRMT

19. ESTUARY INFLOWS and PASSTHRU REQUIREMENTS(All values are in AcFt)

20. LAKE TEXANA STATISTICS(All values are in AcFt)

21. EFFECT OF CHANGES TO AGREED ORDER

22. WATER UTILIZATION

23. Benefits of Lake Texana Water on Reservoir Storage Since Mary Rhodes Pipeline Startup 100 e 80 g a r o t S Historical m 60 e t s y S h t n 40 o M Without f o Lake Texana d n (Estimated) E 20 0 3 4 5 6 7 8 9 0 1 9 9 9 9 9 9 9 0 0 9 9 9 9 9 9 9 0 0 1 1 1 1 1 1 1 2 2 Year

25. Background (cont.) Water provided to the estuaries from the reservoir system under this paragraph shall be released in such quantities and in accordance with such operational procedures as may be ordered by the Commission. Permittees shall provide not less than 151,000 acre-feet of water per annum for the estuaries by a combination of releases and spills from the reservoir system at the Lake Corpus Christi Dam and return flows to Nueces and Corpus Christi Bays and other receiving estuaries.

26. Background (cont.) • Construction Completed 1982 • Inundation Occurred 1987 • Letter of Inquiry Received 1989 • Texas Water Commission Took Jurisdiction in Spring 1990 • Creation of Technical Advisory Committee • TAC—Characterization Study and Final Report to Hearings Examiner

27. Water Use Projections for Corpus Christi Regional Water System

28. Demand

29. Projection Comparison City and TWDB acre-feet

30. Projected and Recent Actual Demand

31. Supply

32. Reservoir System Yield • That amount of water that the reservoir (or reservoir system) could have produced annually if it had been in place during the worst drought of record.

33. Reservoir System Inflows- Lowest 3 Year Periods acre-feet

34. Firm yield assumption-reservoir is used till empty Safe yield assumption-reservoir is left with a volume of reserve supply (6 months of supply) Reservoir System Yield Modeling Assumptions

35. Firm Yield CCR/LCC System (1992 – 2001) 300,000 250,000 200,000 System Yield (acft/yr) 150,000 100,000 50,000 0 1992 1995 1997 1998 2001 Time (Non-Successive Years)

36. Total Supply (2003) Firm Yield Safe Yield 237,000 } 202,932 Texana } Texana CCR / LCC CCR / LCC acre-feet

37. Total Supply Projection (Current Sources) acre-feet

38. Demand and Supply acre-feet

39. Projected and Actual Combined Demand and Supply

40. Demand and Supply

41. SummaryDemand = Supply

42. Future Actions • Continue to use multiple projection methodologies • Compare city’s projections to TWDB’s and other available projections • Continue to update projections on a one-year planning cycle • Optimize existing water supply sources • Continue to develop future water supply sources

43. City of Corpus Christi Desalination Initiatives

44. Padre Island Desalination Project

45. Preferred Facility Siting Preferred RO Facility: Padre Island Pump Station / Nueces County Packery Channel Park Alternate RO Facility Location: At NCWCID4 Pumping Station Alternate ASR Well Location: Mid-Mustang Island Preferred Source Well Location: City-Leased TGLO Land at Packery Channel Preferred ASR Well Location: Near Nueces County Padre Balli Park along South Padre Island Drive

46. Recommended Project • 3.0-mgd project includes: • Chicot Aquifer Horizontal Directionally-Drilled well field • 1.0-mgd RO facility (with buildings and infrastructure to support 5-mgd) • 2.0-mgd ASR capacity • By-Product Disposal via Deep Well Injection (with sufficient capacity to handle 5.0 mgd) • Site work and transmission piping • Upgrades to existing Padre Island Pumping Station • Estimated cost: $23.2 million including contingencies (June 2003 dollars,  30 percent) • Subject to verification/refinement based on results of hydrogeologic and water quality testing program

47. State Desalination Initiative

48. Why Coastal Bend?Why Corpus Christi? • Largest Gulf-front City with a Strategic Port in Texas • Largest Industrial City in Attainment Status for Air Quality • Progressive and History of Long-range Water Planning • Mary Rhodes Pipeline • Water demands met through 2050 • Regional Water System • Proximity to Users • Local and Regional Support

49. City of Corpus ChristiRegional Water System • City of Corpus Christi and Coastal Bend • Serves 75% of M&I Demand for Region N • Supply Water to Suppliers in Seven Counties • Existing Municipal Customers • Existing Industrial Customers • Koch/Flint Hills, Citgo, Valero, Coastal, Equistar • Power Generation • Potential to Supply Future Customers

50. Corpus Christi and Regional Water System