USGS: Pumping may lower groundwater in Edwards-Trinity under Pecos County [Odessa American, Texas :: ]
(Odessa American (TX) Via Acquire Media NewsEdge) Feb. 27--A new study by the U.S. Geological Survey found year-round water pumping for the next 30 years could cause groundwater levels to decrease by as much as 32 feet in parts of the Edwards-Trinity Aquifer in the Pecos County region.
Local government officials and water management authorities commissioned the more than $1 million, two-and-a half year groundwater-flow model so they could better understand the resource and plan for future usage, said Paul Weatherby, General Manager at Middle Pecos Groundwater Conservation District, who described the results as a baseline.
The Edwards-Trinity Aquifer supplies water for agricultural, industrial and public uses such as drinking water. It flows through fractured, porous rock across much of the southwestern part of the state, and average freshwater thickness of the aquifer is about 433 feet, according to the Texas Water Development Board.
But it remained unclear whether the projected declines would amount to a problem, and a USGS researcher said it would be up to the conservation district to determine.
"I don't' know," Weatherby said. "We are just going to keep it in mind and make our basic management decisions."
The study could influence water permitting and it will provide data for another planned study.
The USGS study included analyses of the flow and recharge rates of the approximately 3,400 square mile area, from the Barilla and Davis Mountains to the Pecos River.
Researchers ran three scenarios of water-use demands over a 30-year-period from 2010 to 2040, using a three-dimensional groundwater flow model, according to the report.
"This USGS Edwards-Trinity model will help us to effectively manage and better preserve our valuable water supplies," said Pecos County Judge Joe Shuster in a statement.
Declines from 5 to 15 feet were evident in some areas in each scenario, with the largest projected groundwater-level declines in areas of more intense pumping. Another scenario projected a maximum decline of 27-feet in some areas.
An intense pumping area described in the report was the "Leon-Belding" southwest of Fort Stockton. The Leon-Belding is farmland for crops including pecan orchards, cotton and alfalfa.
"There can be plenty of water in the entire system but there can be local areas within that system with water shortages," said Brian Clark, one of the USGS researchers.
The model comes as outside interest increases in Pecos County water from oil and gas companies, for example, and municipalities.
Clark said the USGS researchers found some water from lower aquifer including the Capitan Reef moves upward into the Edwards-Trinity, meaning that water in some parts of the Edwards-Trinity could be of lower quality.
The City of Odessa last year began and ultimately tabled negotiations with Fort Stockton to buy 50 million gallons of water a day from the lower Capitan Reef aquifer and pump it to Odessa via a pipeline.
Allan Standen, a hydrologist based in Austin, will build upon the research with a study over the next year and is expected to present plans for the study next month to Pecos County Commissioners, Weatherby said.
Standen on Wednesday said he intended to build a more detailed map "that will provide the district with instant information relating to the aquifer and some of the oil and gas" operations.
"Mainly it will just help the district find out when they have a permit application, if they are drilling 1,000 feet: What aquifer do they go through? What formation," Standen said. "You've got to know where you're getting it."
Agencies that helped fund the study were the Middle Pecos Groundwater Conservation District, Pecos County, City of Fort Stockton, Brewster County, and Pecos County Water Control and Improvement District No. 1.
Contact Corey Paul on Twitter @OAcrime on Facebook at OA Corey Paul or call 432-333-7768.
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