5.2.3 Water Management Strategies
Following is a brief description of each of the water management strategies included in the South Central Texas Regional Water Plan along with the associated dependable water supply during drought.
Municipal Demand Reduction (Conservation) (L-10 Mun.)
Management strategy includes municipal water conservation practices and programs to reduce per capita water use in cities by amounts in addition to reductions already incorporated into the TWDB advanced water conservation case water demand projections. Planned additional municipal water conservation focused on public education programs, accelerated retrofit of toilets, and changes in lawn irrigation could effectively increase supply through demand reduction in the South Central Texas Region by about 44,600 acft/yr in the year 2050. Volume III, Section 1.1 includes a detailed discussion of this management strategy.
Irrigation Demand Reduction (Conservation) (L-10 Irr.)
Management strategy achieves water conservation through the installation of Low Energy Precision Application (LEPA) irrigation systems and furrow dikes. Planned implementation of these conservation measures in Bexar, Medina, Uvalde, Atascosa, Frio, and Zavala Counties could effectively increase supply for irrigation through demand reduction by about 28,900 acft/yr after adjustment for planned Edwards Irrigation Transfers (L-15). Volume III, Section 1.1 includes a detailed discussion of this management strategy.
Irrigation Demand Reduction (Conservation) with Transfer (L-10 Irr.)
Management strategy involves voluntary transfer of water conserved through the installation of Low Energy Precision Application (LEPA) irrigation systems and furrow dikes on farms obtaining supplies from the Edwards Aquifer to municipal users. Planned implementation of these conservation measures on about 53 percent of applicable acreage in Bexar, Medina, and Uvalde Counties could effectively increase municipal water supply for Bexar County by about 27,300 acft/yr (85 percent of 32,134 acft/yr), after adjustment for planned Edwards Irrigation Transfers (L-15) and consideration of Critical Period Management reductions during drought.
Edwards Irrigation Transfers (L-15)
Management strategy is based upon the provisions of Senate Bill 1477, as amended, which provides for the creation of the Edwards Aquifer Authority, establishes a withdrawal permit system, and potentially allows a permit holder to sell or lease up to 50 percent of his irrigation rights. Planned voluntary transfers of 50,219 acft/yr (about 53 percent of eligible proposed Edwards irrigation rights in Bexar, Medina, and Uvalde Counties totaling 95,430 acft/yr) could effectively increase municipal water supply by about 42,700 acft/yr (85 percent of 50,219 acft/yr), after consideration of Critical Period Management reductions during drought. Volume III, Section 1.3 includes a detailed discussion of this management strategy.
Edwards Recharge – Type 2 Projects (L-18a)
Management strategy involves the construction of recharge enhancement structures located atop the Edwards Aquifer recharge zone (Type 2 Projects) on streams that are often dry. These structures impound water only for a few days or weeks following storm events and recharge water very quickly to the aquifer, typically draining at a rate of 2 to 3 feet per day. Planned projects include Indian Creek, Lower Frio, Lower Sabinal, Lower Hondo, Lower Verde, San Geronimo, Northern Bexar / Medina County Projects (Limekiln, Culebra, Government Canyon, Deep Creek, Salado Dam No. 3), Salado Creek FRS, Cibolo Dam No. 1, Dry Comal, and Lower Blanco. Consensus Environmental Criteria were applied in the technical evaluations of projects comprising this management strategy located on streams which typically flow. Summaries of applicable instream flow criteria are included in Volume III, Appendix F. Implementation of these projects could enhance spring discharge and increase dependable municipal water supply for Bexar County by about 21,600 acft/yr. It is specifically recognized by the SCTRWPG that alternative projects at these locations that may be larger in size and storage capacity are consistent with the Regional Water Plan. Volume III, Section 2.2 includes a detailed discussion of this management strategy.
Canyon Reservoir – River Diversion (G-15C)
Management strategy involves the purchase of stored water from Canyon Reservoir made available by amendment of Certificate of Adjudication No. 18-2074 to authorize additional diversions. An application for this amendment has been submitted by the Guadalupe-Blanco River Authority (GBRA) and is presently under consideration by the Texas Natural Resource Conservation Commission (TNRCC). Planned implementation of this strategy could include diversion from Lake Nolte, transmission and treatment facilities, and distribution of an additional dependable supply of about 15,700 acft/yr in Comal County.
Volume III, Section 4.1 includes a detailed discussion of a water supply option identified as Canyon Lake Water Released to Lake Nolte – Treated Water to Distribution System or Recharge Zone. The SCTRWPG has considered the utility of this management strategy as a potential new treated water supply to Comal, Guadalupe, and/or Hays Counties in the context of alternative regional water plans (Volume II) and has recommended its implementation to meet projected needs in Comal County in the Regional Water Plan. Estimates of cost and assessments of environmental issues and cumulative effects of implementation are presented herein.
Canyon Reservoir – Wimberley, Woodcreek, and Blanco (G-24)
Management strategy involves the purchase of stored water from Canyon Reservoir made available by amendment of Certificate of Adjudication No. 18-2074 to authorize additional diversions. An application for this amendment has been submitted by GBRA and is presently under consideration by the TNRCC. Planned implementation of this strategy would include diversion from Canyon Reservoir, transmission and treatment facilities, and distribution of an additional dependable supply of about 1,350 acft/yr to the Cities of Wimberley, Woodcreek, and Blanco in rural Hays and Blanco Counties.
Lower Guadalupe River Diversions (SCTN-16)
Management strategy involves the diversion of water from the San Antonio River above the Guadalupe River Saltwater Barrier to two 25,000 acft off-channel reservoirs, transmission to a regional water treatment facility, and distribution in Bexar County. Sources of water include presently underutilized surface water rights held by GBRA and Union Carbide Corporation (up to about 67,200 acft/yr), unappropriated streamflow, and groundwater from the Gulf Coast Aquifer (up to 20,000 acft/yr). Planned implementation of this strategy will provide a dependable supply of about 94,500 acft/yr beginning in 2010. Based on long-term averages derived from monthly simulations over a 56 year historical period, this dependable supply is comprised of 66,200 acft/yr available under existing water rights, 20,200 acft/yr available as unappropriated streamflow, 11,200 acft/yr available as groundwater from the Gulf Coast Aquifer, and a loss of 3,100 acft/yr to net evaporation from the off-channel reservoirs. The off‑channel reservoirs would be located in Refugio, Victoria, or Calhoun Counties proximate to the diversion facilities. Technical evaluations of this management strategy have assumed that this off-channel storage will be in the form of reservoirs created by two “ring-dike” embankments and will have no contributing drainage area. Consensus Environmental Criteria were applied in the technical evaluation of this management strategy. Summaries of applicable instream flow criteria are included in Volume III, Appendix F.
New Colorado River Diversion Option (LCRA)
Management strategy is based on a July 6, 2000 proposal by the Lower Colorado River Authority (LCRA) and involves the diversion of water from the Colorado River near Bastrop and Bay City to off-channel reservoirs, transmission to regional water treatment facilities, and distribution in Hays and Bexar Counties. Sources of water include presently underutilized surface water rights, stored water from the Highland Lakes System, and groundwater from the Gulf Coast Aquifer. Planned implementation of this strategy will provide a dependable supply of about 150,000 acft/yr to the South Central Texas Region in 2050 as well as an additional 180,000 acft/yr to meet irrigation needs in the Lower Colorado Region.
The SCTRWPG has, with certain qualifications, adopted this management strategy and its associated facilities necessary to provide for a new supply of 150,000 acft/yr as proposed by the LCRA and Region K. The recommended management strategy includes approximately 100,000 acft of off-channel storage to be located in Wharton and Matagorda Counties. Estimates of cost have assumed that this off-channel storage will be in the form of reservoirs created by four “ring-dike” embankments and having no contributing drainage area. Potential sharing of costs for such associated facilities is a subject of on-going negotiations. Estimated costs for purchase of water from the LCRA shown in the Regional Water Plan are based on LCRA’s current in-basin rate of $105 acft/yr plus a 25 percent out-of-basin surcharge. Ultimate costs for purchase of water will be a subject of negotiation.
The SCTRWPG has been informed that evaluations of this option have been completed by Region K in accordance with applicable law. The SCTRWPG is also cognizant of various comments and concerns regarding potential effects of this option on instream flows and freshwater inflows to bays and estuaries and has included summary information provided by LCRA regarding potential changes in streamflow in Section 5.2.4. As the quantity of water which may ultimately be made available to Region L by the LCRA and Region K is uncertain at this time, the SCTRWPG has included the originally proposed quantity of 150,000 acft/yr in the Regional Water Plan.[1] More specifically, the Plan includes up to 18,000 acft/yr diverted near Bastrop for delivery to Hays County and up to 132,000 acft/yr diverted near Bay City for delivery to Bexar County.
Carrizo Aquifer – Wilson & Gonzales
(CZ-10C)
Management strategy involves the immediate development of well fields in the Carrizo Aquifer in northern Wilson and southern Gonzales Counties, a collection system, transmission to a regional water treatment facility, and distribution in Bexar County. Strategy has been formulated subject to the rules and policies of the Evergreen and Gonzales County Underground Water Conservation Districts. Planned implementation of this strategy includes annual production of approximately 11,000 acft and 5,000 acft from Wilson and Gonzales Counties, respectively, throughout the 50-year planning period.
Volume III, Section 6.1 includes a detailed discussion of water supply options identified as Carrizo-Wilcox Aquifer between San Marcos and Frio Rivers which involve the potential production of either 40,000 acft/yr or 75,000 acft/yr from new well fields in Wilson and Gonzales Counties. Upon consideration of simulated Carrizo Aquifer drawdown associated with these production rates in the context of alternative regional water plans (Volume II), the SCTRWPG has included the production rate of 16,000 acft/yr in the Regional Water Plan. The cumulative effects of implementation and long-term operation of this management strategy, as included in the Regional Water Plan, are summarized in Section 5.2.4.
Carrizo Aquifer – Gonzales & Bastrop
(CZ-10D)
Management strategy involves the phased development of well fields in the Carrizo Aquifer in northern Gonzales and southern Bastrop Counties, a collection system, transmission to a regional water treatment facility, and distribution in Comal and Guadalupe Counties. Strategy has been formulated subject to the rules and policies of the Gonzales County Underground Water Conservation District and consideration of the draft rules of the Lost Pines Groundwater Conservation District. Well field development in southern Bastrop County is not expected to occur prior to the year 2040. Planned implementation of this strategy includes maximum annual production of approximately 15,000 acft and 12,500 acft from Gonzales and Bastrop Counties, respectively, in 2050.
Volume III, Section 6.2 includes a detailed discussion of a water supply option identified as Carrizo-Wilcox Aquifer between Colorado and Frio Rivers which involves the potential production of 220,000 acft/yr from new well fields in Atascosa, Wilson, Gonzales, and Bastrop Counties. Upon consideration of simulated Carrizo Aquifer drawdown associated with production rates of 58,500 acft/yr and 90,000 acft/yr from Gonzales and Bastrop Counties in the context of alternative regional water plans (Volume II), the SCTRWPG has included a maximum production rate of 27,500 acft/yr in the Regional Water Plan at year 2050. The cumulative effects of implementation and long-term operation of this management strategy, as included in the Regional Water Plan, are summarized in Section 5.2.4. It is noted that the Region L estimates of groundwater production in Bastrop County exceed Region K estimates of availability in and beyond year 2030. The two Regional Water Planning Groups have agreed that discussion of differences will be more productive upon completion of the new Groundwater Water Availability Models presently under development by the TWDB.
Carrizo Aquifer – Local Supply (SCTN-2a)
Management strategy involves the phased development or expansion of well fields in the Carrizo Aquifer for the purpose of meeting local municipal, industrial, steam-electric, or mining needs in Atascosa, Caldwell, Dimmit, and Wilson Counties. Planned implementation of this strategy provides new dependable supplies totaling about 14,700 acft/yr for the South Central Texas Region in 2050.
Simsboro Aquifer (SCTN-3c)
Management strategy involves the phased development and expansion of well fields in the Simsboro Aquifer in Milam, Lee, and Bastrop Counties for the purposes of facilitating on-going mining operations and production of municipal and industrial water supply. Implementation of this management strategy maximizes the beneficial use of water that is pumped to depressurize the mines by developing collection, transmission, treatment, and distribution facilities for use in Bexar County as opposed to being discharged into local streams for disposal. Planned implementation of this strategy will provide a dependable annual supply of approximately 55,000 acft throughout the 50-year planning period.
Projected pumpage associated with this management strategy is consistent with the Brazos G Initially Prepared Regional Water Plan (Milam and Lee Counties) for the entire 50‑year planning period. Projected pumpage in Bastrop County after 2020, however, exceeds the current estimate of available supply adopted by the Lower Colorado Regional Water Planning Group (Region K). Periodic discussions between representatives of the South Central Texas and Lower Colorado Regions have focused on concerns regarding potential water level declines in the outcrop of the Simsboro Aquifer, three different groundwater models of the area, mitigation of impacts to affected wells, and equitable treatment of property owners within a groundwater district. Differences between Region L’s projected pumpage and Region K’s estimate of available supply are more than 20 years from the present while development of new Carrizo (Simsboro) Aquifer Groundwater Availability Models (GAMs) under Texas Water Development Board direction is to be completed by about 2002. Hence, it has been agreed that discussions will be more productive upon completion of the GAMs at which time additional scientific information will be available to both regions.
Volume III, Section 6.3 includes a detailed discussion of a water supply option identified as Simsboro Aquifer – Bastrop, Lee, and Milam Counties with Delivery to a Major Municipal Demand Center which involves the potential production of 75,000 acft/yr from new and existing well fields. Subsequent to the completion this analysis in late 1999, the San Antonio Water System completed a study of its own[2] and recommended that a production rate of 55,000 acft/yr be considered in the technical evaluation of alternative regional water plans in which this management strategy would be included. The cumulative effects of implementation and long-term operation of this management strategy, as included in the Regional Water Plan, are summarized in Section 5.2.4.
SAWS Recycled Water Program (SAWS)
Management strategy involves the phased expansion of SAWS Recycled Water Program to provide dependable water supplies for non-potable uses and meet 20 percent of SAWS projected water demand. Current SAWS Recycled Water Program is capable of delivering about 35,000 acft/yr and consumptive reuse of about 25,000 acft/yr is included as current supply. Planned phased implementation of this management strategy will provide an additional dependable annual supply of about 19,800 acft in 2010 and about 52,200 acft in 2050.
This management strategy involves the continued implementation and expected future expansion of the SAWS Recycled Water Program. Facilities for future expansion are expected to include Southern Interconnections between the Leon Creek, Dos Rios, and Salado Creek wastewater treatment facilities as well as a Northern Interconnection linking the Leon Creek and Salado Creek transmission lines. Costs for expected future expansion are based on actual costs for implementation to-date and are included in the Regional Water Plan.
The SCTRWPG recognizes that SAWS and other water suppliers throughout the region may choose to reuse or reclaim the increased treated wastewater volumes associated with increased municipal water use, especially such wastewater volumes derived from privately owned groundwater and interbasin transfer of surface water. The SCTRWPG further recognizes that this reuse may be accomplished directly (“flange-to-flange”) or indirectly through bed and banks delivery to downstream diversion and/or storage sites subject to applicable low. Such lawful reuse of treated wastewater is consistent with the South Central Texas Regional Water Plan.
Purchase Water from Major Provider (PMP)
Management strategy involves the purchase of water supplies from, or participation in the development of new water supplies with, an identified Major Water Provider. Major water providers include the San Antonio Water System (SAWS), Bexar Metropolitan Water District (BMWD), Guadalupe-Blanco River Authority (GBRA), City of New Braunfels, City of San Marcos, and Canyon Regional Water Authority (CRWA). This strategy may also involve the purchase of water supplies from, or participation in the development of new water supplies with, the Regional Water Provider(s) for Bexar County.
Three purchases of water from major providers have been specifically identified in the Regional Water Plan and total 14,240 acft/yr. The largest of these involves the phased purchase of up to 8,000 acft/yr by Kendall County water user groups from the Regional Water Provider for Bexar County or another major provider. Costs for this management strategy include those for purchase, treatment, transmission, and distribution of water and are based on detailed feasibility studies for the Western Canyon Regional Water Supply Project. The Plan includes a purchase of 5,000 acft/yr by the City of San Marcos from the Guadalupe-Blanco River Authority (GBRA) for diversion at Lake Dunlap and transmission in an existing pipeline to a regional treatment facility at San Marcos. Costs include those for water purchase, expansion of the treatment facility, and distribution. The Plan also includes the purchase of 1,240 acft/yr by the City of Victoria from GBRA. This additional water supply would be delivered from Canyon Reservoir via the Guadalupe River and diverted, treated, and distributed using primarily existing facilities.
Desalination of Seawater (SCTN-17)
Management strategy involves the long-term development of intake and treatment facilities on the north shore of San Antonio Bay near Seadrift and transmission of treated water for distribution in Bexar County. This management strategy utilizes a source of water that is essentially unlimited; however, costs of treatment and location for brine discharge (as may affect marine habitat and species) remain concerns. Planned implementation of this strategy will provide a dependable annual supply of approximately 56,000 acft beginning in 2040 and increasing to about 84,000 acft by 2050. Volume III, Section 1.10 includes a detailed discussion of this management strategy.
The SCTRWPG also considered an alternative water supply option involving desalination of seawater[3] sponsored by the TWDB and the Lavaca Regional Water Planning Group (Region P). This option would include intake and treatment facilities at the Joslin Steam-Electric Station near Point Comfort with additional facilities for transmission to and distribution within Bexar County. The option has not been included in the Regional Water Plan because the intake is located in an estuary reportedly having sediments contaminated with mercury and Polycyclic Aromatic Hydrocarbons[4]. In addition, the Calhoun County Navigation District has communicated to members of the SCTRWPG that the location of such a facility is unacceptable because of potential liability to the District. Should these matters be favorably resolved, the SCTRWPG may consider amendment of the Regional Water Plan at some time in the future.
Aquifer Storage & Recovery (ASR) (SCTN-1a)
Management strategy involves the immediate development of SAWS planned 60 mgd aquifer storage and recovery (ASR) system in southern Bexar County so that supplies available from the Edwards Aquifer in winter months may be stored in the Carrizo Aquifer for subsequent recovery in the summer months, thereby substantially reducing peak municipal demands on the Edwards Aquifer during the summer. Planned implementation of this strategy does not increase overall water supply on an annual basis, but does increase the reliability of current supplies for all municipal water user groups dependent upon the Edwards Aquifer. While Volume III, Section 6.8 includes detailed discussions of similar management strategies, the specific strategy included in the Regional Water Plan is best described in a report prepared for SAWS.[5]
Schertz-Seguin Water Supply Project (SSWSP)
Management strategy involves the development of a well field located primarily in southern Gonzales County by the Schertz-Seguin Local Government Corporation and is currently in the implementation phase. This Corporation will be responsible for creating and operating a wholesale water supply system to serve the long-term needs of these two communities located in Guadalupe and Bexar Counties. Planned implementation of this strategy will provide a dependable annual supply of approximately 20,000 acft.
Western Canyon Regional Water Supply Project (WCRWSP)
Management strategy is currently in the
implementation phase and involves the development of a water treatment plant
west of Canyon Reservoir and a water transmission system to deliver treated
water to project participants. This
strategy is dependent upon the amendment of Certificate of Adjudication No.
18-2074 authorizing additional diversions from
Canyon Reservoir which is currently pending before the Texas Natural Resource Conservation Commission. Planned implementation of this strategy by the Guadalupe-Blanco River Authority will provide a dependable annual supply of approximately 10,500 acft to participants including the Bulverde Utility Company, Apex Water Services, Comal Independent School District, City of Boerne, City of Fair Oaks Ranch, San Antonio Water System, Bexar Metropolitan Water District, and San Antonio River Authority.
Hays/IH35 Water Supply Project
Management strategy is currently in the implementation phase and involves the delivery of stored water from Canyon Reservoir via a diversion facility at Lake Dunlap and transmission pipeline paralleling IH 35 to supply water user groups in Hays County. A regional water treatment plant near San Marcos and a raw water pipeline connecting the plant to Lake Dunlap have been completed to-date. Planned facilities include a potable water pipeline from the San Marcos Water Treatment Plant to the City of Kyle, Creedmoor-Maha, City of Buda, and other county entities.
Lake Dunlap WTP Expansion and Mid-Cities Water Transmission System (CRWA)
Management strategy is a part of the Canyon Regional Water Authority plan, and is currently in the design and construction phase. The Lake Dunlap WTP Expansion and Mid-Cities Water Transmission System will supply approximately 5,200 acft/yr of additional supply to Canyon Regional Water Authority’s member entities which include Crystal Clear WSC, Springs Hill WSC, Green Valley SUD, East Central WSC, City of Marion, City of Cibolo, and BMWD (NE Service Area). The water will be diverted from Lake Dunlap north of the City of Seguin and delivered via a new pipeline network to those participating entities.
Carrizo Aquifer – Bexar & Guadalupe (BMWD)
Management strategy is a part of Bexar Metropolitan Municipal Water District (BMWD) plan. The strategy is being implemented and will supply about 4,000 acft/yr to BMWD to supply to its customers in southern and northeastern Bexar County.
Trinity Aquifer – Bexar (BMWD)
Management strategy is a part of Bexar Metropolitan Municipal Water District (BMWD) plan. The strategy is in the process of being implemented and is estimated to supply about 1,000 acft/yr to BMWD to supply to its customers in Northern Bexar County.
Canyon Reservoir Contract Renewal (GBRA)
Management strategy is renewal of existing contracts with New Braunfels (December 5, 2001 expiration) for 6,700 acft/yr, with San Marcos (July 7, 2047 expiration) for 5,000 acft/yr, with Kyle (December 31, 2038 expiration) for 589 acft/yr, and with Port Lavaca (February 20, 2008 expiration) for 1,500 acft/yr. Other existing Canyon Reservoir contracts remain in force throughout the planning period or are assumed to be renewed upon expiration.
Brush Management (SCTN-4)
Management strategy involves the selective removal of brush from rangeland watersheds in counties of the South Central Texas Region located in the Edwards Plateau Vegetational Area or having significant projected shortages. In other counties, it is assumed that the quantities of brush are not large enough to produce water supply benefits. There are 1.1 million acres of brush infested land in the 12.8 million acre planning region. The practice has been studied, some watersheds have been treated and others are presently being selectively cleared. The Texas State Soil and Water Conservation Board, and agencies of the U.S. Department of Agriculture have landowner cost sharing and technical assistance programs for well-planned wildlife habitat compatible brush management/clearing programs. Although it is not possible to estimate the quantities of water that this strategy would contribute during drought, the strategy could contribute to increased streamflows and increased aquifer recharge during non-drought periods. To the extent that such additions to these water resources are stored for use later, the strategy could contribute to supplies available during drought. The water from this strategy would be available for development or recovery by individual water user groups and by water suppliers that serve several different water user groups.
Weather Modification (SCTN-5)
Management strategy involves the seeding of clouds with silver iodide by licensed professionals to increase precipitation within the planning region. This management strategy has been studied and is being practiced in 15 counties of the region’s 21 county area at the present time. Although it is not possible to estimate the quantities of water that this strategy would contribute during drought, the strategy could contribute to increased precipitation on rangeland and cropland, as well as increasing stream flows and aquifer recharge during non-drought periods. Increased precipitation on range and cropland would contribute directly to crop, livestock, and wildlife production, and in the case of irrigated crop production would reduce the need to apply irrigation water. To the extent that such additions to these water resources are stored for use later, the strategy could contribute to supplies available during drought. The water from this strategy would be available for development or recovery by individual water user groups and by water suppliers that serve several different water user groups.
Rainwater Harvesting (SCTN-9)
Management strategy is the catching and storing of rainwater from roofs of homes and other buildings largely for use at or very near the sites from which the water is caught. The strategy is being used in parts of the South Central Texas Planning Region for household water supplies for both potable and non-potable uses. Although this strategy is limited due to rainfall levels, time of rainfall events, and capacities of storage facilities, the strategy can supply a part, or in some cases all, of the water needed by individual households and business establishments in areas that are too distant or too sparsely settled to be served efficiently by public systems. Rainwater harvesting in the Trinity Aquifer area of the region (Northern Bexar, Comal, Hays, Medina, and Uvalde Counties) can supplement supplies from wells completed in this aquifer, and thereby extend the capabilities of this aquifer to support the demands that are projected to be placed upon it.
Additional Municipal Recycling (Reuse) Programs
Management strategy involves expansion of programs that reclaim municipal wastewater for non-potable uses such as irrigation of golf courses, parks, and open spaces of cities, landscape watering of large office and business complexes, cooling of large office and business complexes, steam-electric power plant cooling, irrigation of farms that produce livestock feed and forage, irrigation of farms that produce sod, ornamentals, and landscape plants, and for instream uses such as river walks and waterways. This strategy is being used within the region by entities including SAWS, SARA, and CCMA and can be expanded as the quantities of municipal wastewater increase with population growth. An advantage of this strategy is that the water has already been developed and brought to the locations of many of the uses listed above. With additional treatment, this water can be reclaimed for further use, as opposed to being discharged for disposal, at a cost to the municipalities that have used it once.
The SCTRWPG recognizes that SAWS, SARA, CCMA, and other water suppliers throughout the region may choose to reuse or reclaim the increased treated wastewater volumes associated with increased municipal water use, especially such wastewater volumes derived from privately owned groundwater and interbasin transfer of surface water. The SCTRWPG further recognizes that this reuse may be accomplished directly (“flange-to-flange”) or indirectly through bed and banks delivery to downstream diversion and/or storage sites subject to applicable law. Such lawful reuse of treated wastewater is consistent with the South Central Texas Regional Water Plan.
Small Aquifer Recharge Dams
Management strategy is the construction of small dams on ephemeral waterways to capture runoff and hold it for seepage into aquifers of the planning region. The strategy is needed and appears to be applicable in the northern parts of the northern counties of the South Central Texas Water Planning Region overlying the Trinity Group of Aquifers that are being heavily stressed by a rapidly growing population. This strategy can be implemented by individual landowners of the area, but would probably need cost sharing by organized groups who obtain and depend upon the aquifers to be recharged, and to the extent that such structures reduce soil erosion, may qualify for technical and financial assistance from state and federal agencies.
Edwards Aquifer Recharge & Recirculation Systems
Management strategy involves artificial recharge of the Edwards Aquifer, capture of the resulting increased springflows, and returning these quantities of water to further recharge the aquifer. Artificial recharge could be done using runoff from the Edwards Plateau, water imported from other watersheds, the subsequent increment of springflow resulting from artificial recharge, and/or a combination of these sources. The purpose of this strategy is to maintain springflows at satisfactory levels to protect the habitats of endangered species that exist in the springs and specified reaches of spring fed streams, while at the same time increasing the quantity of water that can be withdrawn from the aquifer to meet the needs of water user groups. The quantities of water that could be withdrawn from the aquifer depend upon the quantities of recharge, the location(s) at which the recharge is made to the aquifer, levels of the aquifer at the time of recharge, residence time of recharged water in the aquifer, and perhaps other factors that are not known or well understood. The major reason for the Recharge and Recirculation strategy is to use the aquifer to store and distribute water to water user groups that have already established themselves in proximity to the aquifer.
Cooperation with Corpus Christi for New Water Sources
Management strategy involves cooperation and partnership with Corpus Christi of the Coastal Bend Water Planning Region (Region N) in the development of additional or “New Water Sources.” The potentials include desalination, surface water from the Lower Colorado River that might be conveyed via Corpus Christi’s Mary Rhodes Pipeline from Lake Texana to the City of Corpus Christi in exchange for water to recharge the Edwards Aquifer that is now included in Corpus Christi’s permit for Choke Canyon Reservoir, groundwater along and near the Mary Rhodes Pipeline, surface water from the Brazos River Basin via the Mary Rhodes Pipeline, and perhaps other sources in or adjacent to the coastal areas of Regions L and N. In any case, the objective of this option is benefit both regions by improving efficiency and lowering costs of developing New Sources of water for both regions. One of the ways to accomplish parts of this objective is to increase the usage of already existing facilities and sources of water.
Additional Storage (ASR and/or Surface)
Management strategy involves implementing large, regional scale ASR and/or surface storage facilities adequate in size to store surplus flows of surface water during periods of high streamflows, including flood flows, to be available during extended periods of drought. Present management strategies of the South Central Texas Regional Water Plan are sized and scheduled to meet seasonal and daily variations of demand, but some current supplies may not be fully reliable during extended or multi-year droughts. Thus the need for surface reservoirs, large scale ASR Systems, or multipurpose reservoirs. If the water management issue is a supply for emergencies or drought, water could be stored in the Carrizo or Gulf Coast Aquifers for several years before it is recovered. Water treatment capacity necessary to meet peak day demands may be available at non-peak times (fall, winter, and spring) to treat water for aquifer storage and subsequent recovery.
Lockhart Reservoir (G-21)
The Lockhart Reservoir is recommended as a potential reservoir site. Although the Regional Water Plan recommends other means of meeting projected water needs in Caldwell County, the SCTRWPG recognizes the strong interest of the local government in shifting from low-quality groundwater sources to a surface water supply system. The reservoir is considered by the local government to be an important economic development project to create new growth opportunities for the area. There are questions about economic feasibility at present, but the SCTRWPG recognizes the efforts in Caldwell County and by the Guadalupe Blanco River Authority to find a viable strategy to move the project forward. When that strategy is ready, the RWPG will review the Lockhart Reservoir water supply option as a possible amendment to the Regional Water Plan.
[1] On December 14, 2000, late in the planning cycle, additional analysis by Region K of the Colorado River Diversion option with the full application of consensus environmental flow criteria indicated the yield of the project could be reduced by 19,000 acft/yr, resulting in an estimated 131,000 acft/yr of water available for transfer to Region L (Bexar and Hays Counties). The SCTRWPG acknowledges the different yield amounts for this project contained in the Regional Water Plans for Region L and Region K, and acknowledges that the yield of this project may be reduced to 131,000 acft/yr, and that the unit cost could be increased somewhat. This change could affect supplies to Hays County and Bexar County and may necessitate supplying Hays County needs from other sources. However, due to this information being discovered late in the planning cycle, the SCTRWPG decided to retain the project in the Region L Plan with a yield of 150,000 acft/yr, however, this discrepancy between the two regional plans will be addressed early in the next planning cycle. There are adequate “contingency” supplies available wtihin the Region L plan to compensate for the proposed reduction in yield of the project.
[2] HDR Engineering, Inc. and Paul Price Associates, Inc., “Preliminary Feasibility of Options to Deliver Alcoa/CPS Groundwater to Bexar County,” San Antonio Water System, January 2000.
[3] Turner, Collie & Braden, Inc., “Investigation of Joslin Steam Electric Station for Co-Location of a Desalination Facility,” Lavaca Regional Water Planning Group in Conjunction with Region L and N Planning Groups, June 2000.
[4] U.S. Environmental Protection Agency, “Alcoa/Lavaca Bay, Texas,” EPA ID# TXD008123168, EPA Region 6, February 2, 2000.
[5] CH2M Hill, “Aquifer Storage Recovery Project, Preliminary Investigation and Feasibility Analysis Step 2 Report,” San Antonio Water System, February 2000.