Southwest Texas Water Resources Releases Scientific Analysis of Proposed Pipeline

SAN ANTONIO, Feb. 4, 2011 /PRNewswire/ -- Southwest Texas Water Resources, LP (STWR) today released a white paper summarizing more than two years of scientific research on the Southwest Texas Water Project (STWP). The proposed 70-mile regional pipeline would transport a maximum of 40,000 acre-feet of water annually from the Uvalde Pool of the Edwards Aquifer, diversifying San Antonio's water supply by pumping Edwards water from the Uvalde Pool rather than the San Antonio Pool. The research was conducted by STWR and hydrogeologists at Pape-Dawson Engineers, one of the region's premier engineering firms. The research led to the following conclusions:

• The STWP would increase water levels in the San Antonio Pool of the Edwards Aquifer, including spring flows in the environmentally-sensitive Comal and San Marcos springs.
• The STWP would reduce the amount of time users in the San Antonio Pool face water restrictions, while maintaining the reliability of pumping for users in the Uvalde Pool.
• Pumping 40,000 acre-feet for the STWP would result in total pumping from the Uvalde Pool that is significantly lower than both historic pumping and currently permitted amounts.

(Photo:  http://photos.prnewswire.com/prnh/20110204/DA42822)

"This project makes sense both from a scientific and public policy perspective," said Velma Danielson, former general manager of the Edwards Aquifer Authority (EAA) and a consultant to STWR. "At a time when the region is looking to diversify its water portfolio, why not consider all options that can help put the region on a more secure path toward managing and protecting our region's water supply?"

Hydrogeologists used historical data, including the drought of record, and the Edwards Aquifer MODFLOW model to simulate how the Edwards Aquifer system would respond with implementation of a pipeline to transport 40,000 acre-feet of water per year to the San Antonio metropolitan area. The MODFLOW model was created for the Edwards Aquifer Authority by the U.S. Geological Survey and is the same one used by the EAA and the Edwards Aquifer Recovery Implementation Program (EARIP) to determine impacts of various management programs on the Edwards Aquifer. According to the EAA, the MODFLOW model "is considered to be the best tool for evaluating the effects of groundwater management questions in the artesian portion of the aquifer."

Because of the existing pipeline prohibition in the Edwards Aquifer Authority Act, permits originating in the Uvalde Pool are currently being made available for pumping in the San Antonio Pool.  This shift of pumping location concentrates pumping of Edwards Aquifer water closer to the environmentally-sensitive Comal and San Marcos springs and makes San Antonio water users more dependent on the San Antonio Pool of the Edwards Aquifer. STWR's analysis focused on the impacts of reversing that trend and pumping a maximum of 40,000 acre-feet of Uvalde permits from the Uvalde Pool, where they were obtained and historically pumped, and transporting the water to the San Antonio Pool.

Modeled outputs for the entire period of record (1947–2000) show that the pipeline would increase water levels at Well J-17 in the San Antonio Pool by an average of approximately 1.8 feet. Spring flows in the Comal and San Marcos springs would be increased by approximately 9 cubic feet per second (cfs) and 1 cfs, respectively.

During dry times, modeled outputs for the San Antonio Pool for the entire period of record (1947–2000) show the project would result in more months when there are no water restrictions in effect and fewer months when San Antonio Pool users would face Stage I, III, or IV water restrictions. For the Uvalde Pool, modeled outputs for the entire period of record (1947–2000) show the project would result in fewer months that either no stage, Stage II or Stage III of water restrictions are in effect and more months that the most restrictive stage, Stage IV, is in effect.

Actual historic data shows that Uvalde Pool pumpers have never faced water restrictions since the EAA was created in 1993, and water levels in this pool have not declined low enough to require any stage of water use restriction in more than 50 years. In summary, the project would improve conditions in the San Antonio Pool while maintaining the reliability of the Uvalde Pool.

Pumping from the Uvalde Pool peaked in the late-1980s at approximately 150,000 acre-feet per year. Currently, pumping from the Uvalde Pool is approximately 60,000 acre-feet — a 60 percent decline primarily due to improved conservation methods by farmers. Assuming pumping trends remain stable, implementation of the 40,000 acre-feet STWP would result in total pumping from the Uvalde Pool of approximately 100,000 acre-feet, significantly less than both the historic peak of 150,000 acre-feet and the total pumping of 122,000 acre-feet currently permitted by the EAA.

"The model results support the fact that the Southwest Texas Water Project is a resource management tool for the Edwards Aquifer," said Gene Dawson, Jr., P.E., president of Pape-Dawson Engineers. "It would reverse the continued reduction of spring flows at the San Marcos and Comal springs, while maintaining the superior reliability of the Uvalde Pool of the Edwards Aquifer, allowing for better management and long-term use and planning of the region's primary source of water."

The white paper may be viewed at swtexaswaterproject.com in the Project Impacts section.

About STWR

Southwest Texas Water Resources, LP (STWR) is a Texas-based limited partnership working to preserve a reliable water supply and competitive water rates for all businesses and families that rely on water from the Edwards Aquifer. STWR's proposed Southwest Texas Water Project will diversify the region's water supply, enhance water reliability, relieve pressure on Comal and San Marcos springs, help address threats of federal intervention due to the Endangered Species Act and provide an economic boost to Southwest Texas by creating a new water company that constructs and operates a pipeline to move water from the more reliable Uvalde Pool of the Edwards Aquifer to communities in the San Antonio Pool.

SOURCE Southwest Texas Water Resources, LP