Bastrop Water Conflict Turns on Competing Assessments of Aquifer’s Volume
By Christoper De Los Santos
Rural landowners and the Lower Colorado River Authority are locked in a dispute over the effect that pumping underground water from the 4,850-acre Griffith League Ranch in Bastrop County would have on other water wells in the area.
The LCRA wants to ship the water to Lee County, eastern Travis County and the rest of Bastrop County, and it needs permission from the Lost Pines Groundwater Conservation District. Lost Pines has resisted, and the State Office of Administrative Hearings will decide the issue after a hearing on Dec. 19.
The conflict 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, and it won’t disclose their findings before the Dec. 19 hearing. The LCRA asked the Office of the Attorney General, 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 Griffith League Ranch in 2015. On Feb. 1, it applied to the Lost Pines water district for permits to drill eight new wells down to the Simsboro water formation in the Carrizo-Wilcox Aquifer and pump 25,000 acre-feet per year.
The Simsboro formation is much deeper than the formations tapped by surrounding landowners. The LCRA 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 Lost Pines water 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 in the vicinity drop as deep as 810 feet.
The LCRA contends that “thick layers of clay” separate the Simsboro from shallower formations. In contrast, the official groundwater model shows that water passes between the Simsboro and shallower formations.
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 Steve Box, executive director of Environmental Stewardship, which 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 down in the formations; 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. 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.
To give some context to that measurement, the state water board and the Lost Pines district have measured water surface depths in the Carrizo-Wilcox Aquifer since 1987, when it was 137 feet below ground level. That well’s surface dropped to 147 feet and rose to 138 feet, back and forth, every few years for the next 22 years. Since 2009 it dropped to 154 feet, rose to 151 feet and dropped again to 154 feet.
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.
How is the water distributed among the formations and which ones have measurable flows between them?
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 Lost Pines water district.
James Totten, general manager of the Lost Pines water district, and Tom Mattis, city manager in Elgin, are both concerned with overdevelopment of the water formations.
Even Dave McMurry of Aqua Water Supply Corp. voices concern about LCRA’s additional 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 LCRA’s pumping request upon 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 took out a full-page advertisement in the Austin American-Statesman on to tell its side of the story. It simply wants to be prepared to meet the forecasted 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.