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Mid Cibolo Creek

This completed project assessed and improved dissolved oxygen concentrations in Mid Cibolo Creek in South Central Texas to support a healthy aquatic community.

Counties: Comal, Guadalupe, Bexar
Parameters: Dissolved oxygen
Basin: San Antonio River
Segment: 1913

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Background and Goals

TCEQ assessment in 2004 found that in Mid Cibolo Creek in south central Texas, dissolved oxygen were lower than optimal for supporting aquatic life. The program’s South Central Texas Streams project verified that the impairment was severe enough to warrant development of a TMDL for the creek. The goal of the project was to improve dissolved oxygen levels to support use of the creek by aquatic life.

Oxygen, 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 unusually or chronically low levels of dissolved oxygen, which may harm fish and other aquatic organisms.

Watershed Description

Mid Cibolo Creek (Segment 1913) is a 19-mile-long freshwater stream in the San Antonio River Basin. The watershed includes portions of Bexar, Guadalupe, and Comal counties, and the cities of Cibolo, Schertz, Universal City, and Garden Ridge.

In 2006, land use in the watershed was primarily pasture and forest, but was rapidly becoming urbanized due to population growth east of the city of San Antonio. There is little to no water flowing in the upper portion of the creek during the drier times of the year. Flows in the lower portions of the segment are more stable due to discharges from the Cibolo Creek Municipal Authority wastewater treatment facility.


Project staff informed the public about this project through public meetings, which were open to everyone.


While developing the draft TMDL, TCEQ determined that since a single regulated discharger was the primary source of the impairment, it was not necessary to complete and submit a TMDL for Mid Cibolo Creek to EPA.

Upgrades completed to the discharging facility in 2007 did improve dissolved oxygen conditions in the creek. Subsequently, in 2010, TCEQ removed the dissolved oxygen impairment in Mid Cibolo Creek from the state’s 303(d) list of impaired waters. 

Final Reports

Final reports from the assessment are provided below.

Contact the TMDL Program

Email, and mention the Mid Cibolo Creek project in the subject line. Or call us at 512-239-6682. 

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