Occurrence
of Soluble Pesticides in
Barton Springs, Austin, Texas,
in Response to a Rain Event
Water quality at Barton Springs is a critical issue for the City of Austin and its citizens. Barton Springs, located within sight of downtown Austin highrises, is the fourth largest spring in Texas.
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The major set of spring orifices feeds a 225-meter (m)-long swimming pool enjoyed by over 340,000 people per year—Barton Springs Pool is a significant addition to Austin’s quality of life and an important tourist attraction.
Barton Springs provides a part of Austin’s municipal water supply: water from Barton Springs discharges into the Colorado River about 0.6 kilometer (km) upstream of one of Austin’s three water supply plants, at times contributing more than 90 percent of flow in this section of the Colorado River (Slade and others, 1986).
The Barton Springs salamander (Eurycea sosorum), listed as an endangered species by the U.S. Fish and Wildlife Service, lives only in Barton Springs and is vulnerable to changes in water quality (U.S. Fish and Wildlife Service, 1997).
U.S. Geological Survey (USGS) personnel sampled Barton Springs and Barton and Williamson Creeks for soluble pesticides during and after a storm event to determine to what degree ongoing urbanization might be affecting water quality at Barton Springs. Numerous pesticides are used in U.S. urban areas, and some of them are frequently detected in streams (Larson and others, 1999) and shallow groundwater (Kolpin and others, 1998). At higher concentrations, some pesticides can pose a threat to aquatic life and to human health; thus, regulatory agencies have established drinking water standards, health advisory levels, and standards for the protection of aquatic life. The sampling results presented here are for soluble pesticides in streams and springs in Austin, Texas, during and after 2 days of rainfall in May 2000. Analyses include many of the most widely-used pesticides in U.S. agricultural and urban areas, including the herbicides atrazine, prometon, and simazine, and the insecticides carbaryl and diazinon. Previously, soluble pesticides had been detected at Barton Springs on only two occasions: in 1978, diazinon was detected at a concentration of 0.03 microgram per liter (mg/L), and in 1989, prometon was detected at a concentration of 0.1 mg/L. The diazinon sample was likely collected during baseflow, and the prometon sample was likely collected during stormflow (City of Austin, unpublished data). Since those samples were collected, analytical methods have improved, more compounds can be analyzed, and the amount of developed land in the Barton Springs watershed has increased.
| Hydrology of Barton Springs | Methods | Results | Background Information | Update |
For
more information, contact:
Barbara J. Mahler, Research Hydrologist
U.S. Geological Survey
1505 Ferguson Lane
Austin, TX 78754
(512) 927-3566 (telephone)
(512) 927-3590 (fax)
or e-mail: Barbara J. Mahler