The groundwater conservation district responsible for management of the Trinity Aquifer in northern Bexar County continues to gather data in hopes that it will help shape the desired future conditions of aquifers in a nine-county area.

All the GCDs in the nine-county Groundwater Manage-ment Area 9 face a September 2010 deadline to submit the GMA’s Desired Future Conditions to the Texas Water Development Board. The TWDB will determine managed available groundwater – the amount of acre-feet of groundwater that can be pumped in each GMA in Texas – based on the DFC.

George Wissmann, general manager of the Trinity-Glen Rose Groundwater Conserva-tion District that covers Bexar County north of Loop 1604, broadly described the DFC as “what we want the aquifer to look like in 50 years.” Desired future conditions take water levels, water quality, spring flows, water in storage and other factors into account.

Though some groundwater conservation districts want to submit the data well before the deadline, Wissmann said he would prefer to use as much time as possible.

“Some GCDs want it in place ahead of time, but we want to get more data, more studies and more information about how the aquifer works,” he said.

An example of data that would benefit the DFC was presented to the Trinity-Glen Rose GCD board of directors during its Sept. 11 meeting, when James Beach, a senior associate with the groundwater resource development and management firm LBG-Guyton Associates, gave a presentation on water modeling efforts for the district.

Beach said the Texas Water Development Board has incorporated higher recharge numbers – about 80,000 acre-feet per year – into the next version of the groundwater availability model, or GAM, for Groundwater Management Area 9 as a result of the district’s efforts. The original model did not include recharge from Cibolo Creek.

He described the Cibolo Creek in northern Bexar County as a “losing stream” that recharges the Trinity Aquifer at a rate of 235 acre-feet per day when it is flowing. However, he also said the Cibolo does not flow continuously.

Beach said the Trinity’s average estimated recharge from 1950 to 2000 was 75,500 acre-feet per year, but he also said recharge “varies significantly from year to year.”

Beach told Trinity-Glen Rose directors that the effort to develop desired future conditions for GMA 9, which stretches roughly from western Travis County and northwestern Hays County to Kerr and Bandera counties, has resulted in spirited discussion.

“It has taken on a lot more flavored discussion and debate than people thought it would,” he said.

At a recent GMA 9 meeting in Kerrville, where desired future conditions for three small Blanco County aquifers were approved, representatives of environmental groups and other organizations as well as property owners expressed concern that data from the 1950s “drought of record” is not included in the GMA’s groundwater availability model. The drought of record, which began in 1949 and continued through the mid-1950s, was characterized by low rainfall and excessively high temperatures.

That concern along with worries about the impact of development on water resources have been consistently voiced to Trinity-Glen Rose directors at their monthly sessions. Northwest Bexar County residents have also emphasized the need for more data from their area to include in the model. Beach in his presentation acknowledged the lack of information in western Bexar County.

Wissmann said the district intends to add a monitoring well in Northwest Bexar County as part of its effort to compile more data.

“We are a young district,” he said. “We only have so much data. We’re not just focused on the east side of Bexar County.”

Wissmann said the district wants the TWDB to use an accurate groundwater availability model to guide water management efforts in the future.

“We want to make sure that water is available and that properties aren’t impacted,” he said.

Wissmann also said he does not foresee much more development in northern Bexar County that will use water from the Trinity. The San Antonio Water System draws water from the Trinity in the area north of Loop 1604 from Bulverde Road east to U.S. Highway 281. The Bexar Metropolitan Water District also uses Trinity water north of Loop 1604.

In addition to hearing Beach’s presentation at Sept. 11, Trinity-Glen Rose directors approved a $129,000 budget for 2008-09. The district derives almost all of its income from well production fees.