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Mid Cibolo Creek: A Project for Dissolved Oxygen

A completed project to assess and improve dissolved oxygen concentrations in Mid Cibolo Creek in South Central Texas

photo of Mid Cibolo Creek

Mid Cibolo Creek

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

On this page:

Background and Goals

In Mid Cibolo Creek in south central Texas, water quality testing found low concentrations of dissolved oxygen. The program’s South Central Texas Streams project verified that the impairment was severe enough to warrant development of a TMDL for the creek.

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.

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Public Participation

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

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

Upgrades completed to the discharging facility in 2007 ameliorated the low dissolved oxygen conditions in the creek. Subsequently, in 2008, the dissolved oxygen impairment in Mid Cibolo Creek was removed from the state’s 303(d) list and reclassified to Category 4b, which lists water bodies in which a standard is not met, but for which a TMDL is not required because other control requirements are reasonably expected to result in the attainment of the standards. See the most recent Texas Integrated Report of Surface Water Quality for the latest assessment information on Mid Cibolo Creek.

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Reports and Other Documents

Final reports (in PDF) from the assessment are provided below.

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For More Information

For additional information regarding this project, please e-mail us at, and mention the Mid Cibolo Creek TMDL in the subject line. Or call us at 512-239-6682. 

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communities working together taking care of our rivers, lakes, and bays