The Lower Colorado River Authority has denied a request to disclose its hydrological findings in a groundwater dispute with rural landowners in Bastrop County.
The LCRA has requested to pump 25,000 acre-feet of groundwater, or 8.1 billion gallons, per year from the Simsboro formation in the Carrizo-Wilcox Aquifer for customers in Bastrop, Lee and eastern Travis counties, a pursuit that has prompted disquiet among landowners concerned about how that extraction would affect domestic and agricultural wells. But the hydrological science behind LCRA’s decision remains to be seen. Last month, the authority declined to reveal its hydrological reports, testing methods, testing equipment and analytical models.
The Bastrop County dispute turns on questions of hydrology: How much waters is down there? How is the water distributed among layers of clay? Are the water formations connected to each other or discrete?
State law gives the Texas Water Development Board the responsibility to maintain groundwater availability models used in resolving those sorts of questions, according to Larry French, the board’s groundwater director. Along with local and regional water conservation districts, the state board builds the models “based on the best science available for the purpose of developing water resources,” French said.
LCRA has hired its own experts to find answers, but hasn’t disclosed those findings as the case advances to judges with the State Office of Administrative Hearings. The LCRA asked the the Attorney General’s Office, which by state law settles disputes over public information requests, to confirm its argument that it can withhold the report under various exceptions provided in the Texas Public Information Act.
Regardless of how the attorney general’s office rules, French takes a dim view of the LCRA’s competing model.
“It would be very difficult for any person, group or agency to develop a [groundwater availability model] in secret — without peer review, without stakeholder agreement — and have that model accepted for regulation, development or litigation,” French said.
The LCRA bought the groundwater development rights on the 4,850-acre Griffith League Ranch in 2015. In early 2018 it applied to the Lost Pines water district for permits to drill eight new wells and pump 25,000 acre-feet per year.
The Simsboro formation is much deeper than the formations tapped by surrounding landowners. The LCRA has proposed to drill 1,400 to 1,600 feet deep, according to Andrew Donnelly, a senior hydrologist with Daniel B. Stephens & Associates Inc. in Austin, which does work for the Lost Pines Groundwater Conservation District.
Lost Pines records show that in the vicinity of the proposed well field, most of the existing wells for homeowners, farmers, ranchers and small businesses extend less than 600 feet deep. Only two or three existing wells drop as deep as 810 feet.
The LCRA contends that “thick layers of clay” separate the Simsboro from shallower formations. In contrast, the state’s official groundwater model shows that water passes between the Simsboro and shallower formations, said Steve Box, executive director of Environmental Stewardship, a Bastrop-based environmental advocacy group.
How much water is available?
French said the official model “describes the Carrizo-Wilcox Aquifer and the Simsboro water formations as extending from south of the Rio Grande in Mexico, across Texas and into Louisiana — generally following the shape of the coastline.”
Neither the Carrizo-Wilcox nor the Simsboro are caverns filled with water. They are not underground lakes, said Box, who opposes the LCRA request.
“These ground water formations are like what you would get if you poured water into a bucket of sand,” Box said. “The water fills the spaces between the sand grains.”
The water board does not measure the amount of water in the formations, instead it measures the depth below ground at which the formation begins. The deeper a water formation begins, the more water has flowed elsewhere naturally or been depleted by pumping. The Lost Pines water district conducted measurements of the Carrizo-Wilcox water formations in Bastrop County just over a year ago showing 154 feet below ground level.
The Lost Pines district’s most recent modeling of natural inflows and outflows, in March 2017, shows an inflow of nearly 43,000 acre-feet annually, with outflows to springs, rivers, lakes and other water formations of about 50,000 acre-feet.
Below the surface of the Griffith League Ranch, where LCRA proposes its new well field, three water formations exist: the Carrizo, the Wilcox-Calvert Bluff and the Wilcox-Simsboro.
The state’s official groundwater model shows the three formations have measurable flows between each other, Box said.
French said the LCRA pumping application is one of many that would draw from the water formations under the Lost Pines water district.
Lost Pines Groundwater Conservation District General Manager James Totten and Elgin City Manager Tom Mattis are both concerned with overdevelopment of the water formations.
Dave McMurry of Aqua Water Supply Corp. has also voiced concern with the LCRA’s pumping request. “LCRA’s wells will have a significant long-term effect on a number of Aqua’s wells and local residential wells,” McMurry said. Aqua Water Supply Corp. provides water to homes, farms, ranches and businesses in Bastrop County and parts of adjacent counties.
Environmental Stewardship hired independent hydrologist George Rice to analyze the impact of the LCRA’s pumping request on the surrounding water formations. Rice used the official groundwater model to make projections out to 2060. “Pumping from the Simsboro will pull from the overlying and underlying formations,” he concluded.
The LCRA has said it simply wants to be prepared to meet the forecast future demand of residents, ranchers, farmers and business as more and more people continue to move into the area surrounding Austin. It remains committed to conserving and reclaiming natural resources, it said.
“As a regional water provider, the Lower Colorado River Authority is committed to managing and increasing our region’s water supplies,” LCRA’s Executive Vice President for Water John Hofmann said during a September public meeting.
“Modeling by the district’s geoscientist shows the aquifer can supply the full 25,000 acre-feet of water requested in the applications without harming the aquifer,” he said.
Reporting Texas is a digital media initiative by the School of Journalism at the University of Texas.
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