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Atascosa River: Evaluating the Aquatic Life and Recreational Uses

A completed assessment project to evaluate concentrations of dissolved oxygen and bacteria in the Atascosa River in South Central Texas
photo of monitoring in the Atascosa River
Atascosa River
map of the Atascosa River Segment 2107 watershed

Counties: Atascosa, Bexar, Frio, Karnes, Live Oak, McMullen, Medina, Wilson
Parameters: Bacteria and Dissolved Oxygen
Basin: Nueces River
Segment: 2107

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Water Quality and Watershed Description

The Atascosa River watershed flows from its origin in Atascosa County for about 103 miles into Live Oak County, between Choke Canyon Reservoir and the town of Three Rivers, where it joins the Frio River.

The Atascosa River is in the Nueces River Basin, and its watershed includes Atascosa River Park in Pleasanton and the communities of Lytle, Poteet, Pleasanton, Jourdanton, and Christine. The area is heavily used for recreational deer and quail hunting.

Water quality testing in 1996, and again in 2006, found elevated levels of bacteria and low concentrations of dissolved oxygen. 

High concentrations of bacteria may indicate a health risk to people who swim or wade in the rivers—activities referred as “contact recreation” in the state’s Standards for surface water quality. Dissolved oxygen is essential for the survival of aquatic life, and so is used to indicate whether conditions support the “aquatic life use” in the Standards. 

The contact recreation and aquatic life uses were presumed in the Texas Surface Water Quality Standards for the Atascosa River in 2006, rather than being based on site-specific conditions.

In 2008, TCEQ decided to evaluate the aquatic life and contact recreation uses for the Atascosa River at the same time to gain a fuller understanding of the biological and flow conditions for the entire stream. The TMDL Team managed two studies—a survey to support a recreational use attainability analysis (RUAA) and an aquatic life use attainability analysis (ALUAA) for the river.

Use attainability analyses (UAAs) assess the physical, chemical, and biological factors that determine whether a particular use is attainable in a particular water body. A recreational use survey looks at how people actually use a stream for recreation, and evaluates stream characteristics that discourage or encourage water recreation.

The TCEQ worked with the Nueces River AuthorityExit the TCEQ, the Texas Institute for Applied Environmental Research (TIAER)Exit the TCEQ, Texas AgriLife ExtensionExit the TCEQ, and other stakeholders to evaluate the watershed and develop a strategy for continued management of water quality.

Status and Activities

TIAER carried out the RUAA and ALUAA studies under contract with TCEQ. They collected water quality data for the ALUAA from June 2010 to October 2011, and submitted a final ALUAA report to TCEQ in 2012. TIAER submitted the final report on recreational uses in December 2010.

Based on the findings in the ALUAA, TCEQ divided the Atascosa River into three different units in the 2014 Standards: one unclassified waterbody (intermittent flow with perennial pools) and two classified segments, 2107 and 2118. These three new units are defined in Appendix D (the unclassified unit) and Appendixes A and C (2017 and 2118). Also in the 2014 Standards, TCEQ recommended a high aquatic life use for the Lower Atascosa River (Segment 2107) and an intermediate aquatic life use for the Upper Atascosa River (new Segment 2118). These recommendations were submitted to the EPA in 2014 and approved by them in March 2020. 

TCEQ has not yet proposed revisions to the recreational use standards for Segments 2107 and 2118, since EPA did not approve the proposed new segment boundaries until March 2020. However, the RUAA report is available (see link under "Reports"). Contact the TCEQ Standards Team to inquire about the status of these analyses.

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Public Participation

Texas AgriLife coordinated public participation in this project. Public meetings were held in the watershed to seek advice from people who represent government, permitted facilities, agriculture, business, environmental, and community and private interests. TCEQ also encouraged local involvement with the help of the Basin Steering Committee of the Nueces River Authority, part of the Texas Clean Rivers Program.

Reports

The TCEQ Standards Team will use these reports to analyze use attainability and decide whether to recommend revisions to the standards.

ALUAA Report for the Atascosa River

RUAA report for the Atascosa River

Final reports from the 2004 assessment to determine the extent and severity of impairments to the recreational and aquatic life uses of the river are provided below.

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Contact the TMDL Program

Please email tmdl@tceq.texas.gov and mention the Atascosa River project in the subject line. E-mail the TCEQ  to inquire about the status of the UAAs. Or call us at 512-239-6682.

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