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Lower Leon Creek: Aquatic Life

This completed project collected dissolved oxygen samples in Lower Leon Creek and added to the data available for evaluating the aquatic life use.
photo of Lower Leon Creek
Leon Creek below the Kelly Air Force Base site

County: Bexar
Parameter: Dissolved Oxygen
River Basin: San Antonio
Segment: 1906

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Background and Goal

In 2006, TCEQ assessment indicated that low dissolved oxygen concentrations in the creek were not optimal for aquatic life. Oxygen gas, which dissolves in water, is essential for the survival of aquatic life. While the amount of dissolved oxygen in water fluctuates naturally, various human activities can cause chronically low levels of dissolved oxygen.

The goal of this project was to collect additional dissolved oxygen samples to update and add to the data available for evaluating attainment of the aquatic life use of the creek.

Watershed Description

Lower Leon Creek, Segment 1906, drains an area of 228 square miles and has a total continuous length of 57 miles. It originates as a spring-fed stream in the Edwards Plateau region of south–central Texas. The creek runs from its headwaters in northern Bexar County to its confluence with the Medina River. The creek generally flows south and enters the main portion of the Kelly Air Force Base (AFB) from the northwest, near the intersection of Billy Mitchell Road and Westover Road.

Leon Creek drains a highly urbanized residential area and the Kelly and Lackland AFBs. Water quality in the creek is affected by industrial and municipal wastewater discharges and stormwater. The project watershed included the cities of San Antonio, Cross Mountain, Helotes, and Leon Valley.


The University of Texas at San Antonio (UTSA), under contract with the TMDL Program, collected dissolved oxygen data at several stations in on the stream segment that had few samples or older data sets. UTSA completed additional data collection in 2014. The impairment of the aquatic life use for the creek was subsequently removed from the state's list of impaired waters in 2016.

Public Participation

TCEQ staff informed stakeholders about this project through the San Antonio River Authority, which is the Texas Clean Rivers Program partner for the basin.

Contact the TMDL Program

Please email and mention the Lower Leon Creek aquatic life project in the subject line. Or call us at 512-239-6682.

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