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

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.

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.

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. …”

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.”

Certificate of Adjudication No. 21-3214, 1984 - 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.

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 Creates NEAC Whose Mission is to “Consider Such Additional Information and Related Issues and to Formulate Recommendations for the Commission’s Review and Actions.”

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.

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)

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

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

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

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.

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

Choke Canyon / Lake Corpus Christi Reservoir System Daily Pass-Through Status Report Report Date: May 28, 2002 RESERVOIR STATISTICS

Weather Related Information

STREAM FLOWS

USGS Gauge Locations NRMT

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

LAKE TEXANA STATISTICS (All values are in AcFt)

EFFECT OF CHANGES TO AGREED ORDER

WATER UTILIZATION

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

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.

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

Water Use Projections for Corpus Christi Regional Water System Salutation Introduce Panel Members Demand (Sources and Methodologies) Supply Definitions and Current Supply Current Demand and Supply

Demand

Projection Comparison City and TWDB Supply Regional Water Plan One-period growth rate equation (High-Case) Linear Regression Method (Low-Case) These are different ways of estimating use. Difference here is the use of open ended contracts for wholesalers and untreated water customers. Contracts call for their maximum use to be the highest three yr. average + 10 percent. Regional Plan identified about 10K AF of needs from cities that would not be able to meet the new stricter arsenic standard and could possibly be looking our way to meet that need. We feel we capture that with our 8 percent planning margin which equals 10K AF acre-feet

Projected and Recent Actual Demand

Supply

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. That volume of water you can reliably depend on each year during the worst drought or drought of record. The Drought of Record is the dry period between times like now when the reservoirs are at full capacity (approximately 84 months).

Reservoir System Inflows- Lowest 3 Year Periods Each drought is getting more severe as measured by the lowest 3 year periods of inflow in each drought Droughts of the 50’s, 60’s, 80’s, and 90’s. We live in an area dominated by worsening drought and punctuated by short wet periods. acre-feet

Reservoir System Yield Modeling Assumptions Safe yield assumption-reservoir is left with a volume of reserve supply (6 months of supply) Firm yield assumption-reservoir is used till empty Safe yield assumptions could be 4 month reserve or 12 mo or 10 percent of reservoir capacity. For the purposes of planning our water resource needs ( a basic necessity) we are applying both a firm yield and safe yield when considering supply in the reservoir system We can’t assume for planning purposes, that all of the volume in a reservoir is usable, or that we could use all of the reservoir volume till empty. We don’t think it’s reasonable to assume that during a drought of record the reservoir would be used till empty. Drought periods are getting more severe over time, this is an area dominated by drought with occasional wet periods. It becomes a question of quality. You may not run out completely (and this is true for many natural resources) at some point it becomes too expensive to treat and use.

Firm Yield CCR/LCC System (1992 – 2001) 300,000 250,000 Captures the variability of firm yield calculation. It can change due to a number of reasons. For example... 1992 (HDR) Phase II CCR/LCC System Operations Policy 1992 Interim Order HDR/TNRCC Hydrology (1934 – 1989) 1995 (HDR) 1995 Agreed Order (the pass through plan) 1997 (HDR) Phase IV CCR/LCC System Operations Policy lower LCC and less evap and more opportunity to capture 1995 Agreed Order 1998 (HDR) Phase IV CCR/LCC System Operations Policy HDR/TNRCC Hydrology (1934 – 1997) 2001 (HDR) 2001 Agreed Order 200,000 System Yield (acft/yr) 150,000 100,000 50,000 1992 1995 1997 1998 2001 Time (Non-Successive Years)

} } Total Supply (2003) Firm Yield Safe Yield 237,000 202,932 Texana Two Bar Graphs Compare differences between FY and SY Seen on the bottom shaded portions of each. For FY 183,160 For SY 149,069 The other shaded portions are the same for both cases… 31,400 Firm Texana water purchased and delivered through the Mary Rhodes Pipeline. 10,400 also delivered through MR Pipeline is temporary in that it allows for growth in Jackson County 4,500 acre-feet was recently purchased interruptible water And our totals supply is shown under FY 229,500 AF under SY 195,432 AF What do each of these look like over time? Texana CCR / LCC CCR / LCC acre-feet

Total Supply Projection (Current Sources) These are the two different levels seen on the previous graph The decrease over time due to sedimentation of the reservoirs. acre-feet

Demand and Supply acre-feet Finally we examined where demand overcomes supply It depends on whether you’re looking at a firm yield assumption or a more realistic safe yield assumption. When we compare the Demands using the 1PGR and LR to the Firm Yield Result: Demand overcomes supply as early as 2036 Demand overcomes supply as late as 2048 Under Safe Yield Methodology Demand overcomes supply as early as 2025 Demand overcomes supply as late as 2030 We end up with this polygon or quadrangle or quadrilateral shaped area that represent our worst and best case water resource scenarios. acre-feet

Projected and Actual Combined Demand and Supply

Demand and Supply

Summary Demand = Supply 2028 Safe Yield/ Higher Demand 2034 Safe Yield/ Lower Demand 2038 Firm Yield/ Higher Demand 2052 Firm Yield/ Lower Demand Slide Increased future economic opportunity is only one cost of not meeting your needs. The costs of not meeting your needs are tremendous. The costs of not meeting a city’s water resource needs far outweigh the capital costs to meet needs.

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 Slide Increased future economic opportunity is only one cost of not meeting your needs. The costs of not meeting your needs are tremendous. The costs of not meeting a city’s water resource needs far outweigh the capital costs to meet needs.

City of Corpus Christi Desalination Initiatives

Padre Island Desalination Project

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

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

State Desalination Initiative

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

City of Corpus Christi Regional 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

Corpus Christi and Regional Water System

Texas Coastal Bend Project Description 25 mgd seawater desalination facility Located at Barney Davis Power Plant Deliver potable water to Corpus Christi Regional Water System Ability to Expand Existing Marine R&D facilities Hart Foundation A&M UTMSI

Barney Davis Plant Site and Corpus Christi Distribution System A&M /UTMSI Existng Marine Research Facilities A&M /UTMSI Existing Marine Research Facilities Oso Bay

Barney Davis Intake Outfall 1.5 mile Pipeline

COE Nueces River Basin Feasibility Study

US Army Corps of Engineers Reconnaissance Study of the Nueces Basin Watershed Federal funds are available through Corps of Engineers (COE) for projects which include “Ecosystem Restoration” or “Flood Damage Reduction” Federal funds can pay for up to 50% of study cost and 65% of construction costs Projects can include water supply

Important Ecosystems Dependant on Nueces River System Hill Country Streams and Associated Springs Nueces Delta and Estuary 15

US Army Corps of Engineers Reconnaissance Study Identified 10 Projects Flooding downstream of Lake Corpus Christi and throughout the Nueces Basin Recharge enhancement Cotulla diversion projects to enhance storage in LCC/CCR system Two-way pipe project to enhance storage in LCC/CCR system Desalination Treated effluent placement in Nueces Delta Water quality in Choke Canyon reservoir Stream restoration in the upper Nueces Basin Brush management Exotic aquatic plant removal

Projects Selected to Move Forward to Feasibility Phase Desalination -Locally and regionally supported concept. Originally studied in the Coastal Bend Regional Water Plan is sited next to an existing power plant to minimize power costs and reduce treatment costs utilizing heat from the plant. Also combines brackish groundwater with seawater to reduce concentration of TDS in brine, through existing plant discharge facilities. Cotulla diversion -Water quality enhancement, water supply and possible flood damage reduction project bypasses high channel losses in the braided reach and increases storage capacity. Two-way pipeline -Conveys releases over 33cfs with very little losses, creates opportunity for more freshwater inflow by increasing reservoir storage. Higher lake levels improve water quality. Development of off-channel storage site with a pump station would provide flood control benefits to the Nueces delta and could increase firm yield to regional suppliers with less evaporation loss. Wastewater diversions -Take treated effluent from one or more of the City’s municipal wastewater treatment plants and discharges it into critical areas of the delta to help restore the balance of freshwater and nutrients, studies show a potential increase in biological productivity of 3 to 5 times. Recharge enhancement projects -Would contribute significantly to the spring flow, reduce the possibility of the springs going dry, protecting the ecosystem. Would require mitigation to the City. A portion would be used for water supply. Brush control -would use plowing, grubbing and dozing as well as herbicides and controlled burns to control the dominance of trees and brush, resulting in increased stream flow and aquifer recharge. Desalination project at Barney Davis Cotulla diversion to enhance Choke Canyon storage Two-way pipe project between CCR and LCC to minimize channel losses Additional wastewater diversions to Nueces River Delta Recharge enhancement projects with appropriate mitigation for City Brush control

Study Participants Co-sponsors Army Corps of Engineers City of Corpus Christi San Antonio Water System (SAWS) San Antonio River Authority (SARA) Guadalupe Blanco River Authority (GBRA) Nueces River Authority (NRA) Other Interested Parties Edwards Aquifer Authority (EAA) Region N Water Planning Group (Region N)

City Permitting Requirements, Time and Effort Planned Padre Island Desalination Permits for hydro-geologic borings and permit validation studies Allowance of $1M, 100 percent City Expense Two Desalination Projects at Barney Davis Expected to benefit from TWDB’s RW Beck Report South-most Brackish, Freeport, Padre Island Experience will be used

Permitting Requirements City Time and Effort Planned Cont. Additional Wastewater Diversions to the Nueces Delta City has expended extensive time and resources to investigate and establish baseline information for use in possible expansion wastewater diversion projects.

Questions?