Summer 2009 - Guadalupe-Blanco River Authority

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, continuedThis year, the aquifer level dropped more than 30 feet from the670 feet msl recorded Jan. 8, the high point for the year, to 641 inearly July at the J-17 test well in San Antonio. A drop below 640 willtrigger “Stage 3” drought restrictions for San Antonio Water System(SAWS) customers and other pumpers. That meant thatwatering with irrigation systems, sprinklers and soakerhoses was only allowed once every two weeks, amongother restrictions already in place for stages 1 and 2,triggered when the aquifer level fell below 660, then 650.Both the Comal and San Marcos Rivers merge with theGuadalupe and become an increasingly high percentageof the water in the river during drought.With sparse rain, the springs that feed the riverfrom the Edwards Aquifer amounted to an increasingpercentage of the stream flow. But with the aquifer leveldropping daily, the springs continued to wane, becausewhen the water level drops in the Edwards Aquifer, theflow of water from its springs decreases.“This is one of the most intense periods of lack ofrainfall that we’ve ever gone through,” said Thomas Hill,chief engineer for GBRA. “When you start losing thesprings, it has a significant impact on the flow ofthe river.”Flow in the Comal River in New Braunfels, fed by ComalSprings, dropped by more than one-third since mid-March. The flow from San Marcos Springs was thelowest it had been since the drought of 1996, and thatwas taking a toll on the San Marcos River, home of anendangered plant, Texas wild rice.Wildlife officials in late June began taking emergencymeasures in the San Marcos River to rescue Texas wildrice plants by transplanting them from areas ofthe river with water levels inadequate for theirsurvival, to nearby areas in the river where thewater was deeper.“We hate to do it, and the only reason we aredoing it is because these plants are high and dry,and we need to move them to deeper water,” saidMara Alexander, a botanist with the U.S. Fish andWildlife Service’s San Marcos Fish Hatchery andTechnology Center.The Blanco River, which also flows into theGuadalupe, also continued to diminish. It haddropped to 5 cfs at Wimberley in early July, afraction of its median flow of 65 cfs.The low flows downstream were causingsome fish to die, after being trapped in oxygendepletedpools cut off from the stream. Somepeople mistakely assumed that some type ofpollution killed the fish, said Debbie Magin, director of Water QualityServices for GBRA.Photo by Bill WestThis segment of the Guadalupe River above Canyon Reservoir was down to a trickle in July, with the flowmeasuring 2.5 cfs.14
Texas. According to the NationalWeather Service, the Pacific appearedto be warming in June and early July,returning to “El Nino,” a periodicwarming of the currents, which tendsto bring more rain to Texas.So it is possible to see increasedchances for precipitation asfall approaches.Meanwhile, one positive aspectof the drought is that scientists thistime were prepared to gather datafor understanding its effects and theeffects of future droughts."That will prove useful for thedevelopment of the Edwards AquiferRecovery Implementation Program(EARIP), which is charged withdeveloping a long-term environmentalplan for the aquifer", said RobertGulley, EARIP program manager.Photos by LaMarriol Smith“As the flow in the river goes down, more and more areas of the riverare cut off from the main flows,” Magin said. “Fish get trapped in theseisolated pools and die. It’s not because of anything toxic. It’s becauseof no oxygen being added.”The low flows combined with high temperatures also can promotethe growth of blue-green algae, which has an odor. Those areas ofwater also tend to have high levels of bacteria, which swimmers shouldavoid, and especially avoid diving and other activities that force waterinto the nasal passages, she said.“If there is a color to the water that’s not what they normally see, or ifthere is an odor, I would avoid that area,” Magin said. “They’ve got touse their understanding of how the water is supposed to be.”When the June rains didn’t come, the string of 100-degree days wasmaking its mark throughout the region.“One thing that has us concerned is that these are the kinds ofconditions you will typically encounter in August or September,” saidTodd Votteler, GBRA’s executive manager of intergovernmental relationsand policy. “We encountered this in June, usually a heavier rain period.It foreshadows that we could have a really bad summer.”“Droughts are normal,” said Norman Boyd, San Antonio Bayecosystem leader for the Texas Parks and Wildlife Department. “Theyare part of the territory. The concern is how long it’s going to be hereand how long the salinity is going to be high.”Most things return to normal after a drought ends, but some of theseafood populations may take a while to bounce back, Boyd explained,adding, “And that has an impact on the communities that depend onthose resources”Meteorologists generally attribute the drought to “La Nina,” a periodiccooling of the currents in the Pacific, which leads to dry periods in15Recreational tubers try to navigate down the Guadalupe River near Sattler where therelease rate from Canyon Reservoir was 61 cfs in mid-July.
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Summer 2009 - Guadalupe-Blanco River Authority

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