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Clear Creek: A TMDL Project for Chlordane

A completed project to address reduce chlordane in fish and protect the safety of consumers. The total maximum daily loads (TMDLs) are adopted and the implementation plan (I-Plan) is approved.

photo of Clear Creek Above Tidal
Clear Creek Above Tidal

Counties: Brazoria, Fort Bend, Galveston, and Harris
Parameter: Chlordane
River Basin: San Jacinto–Brazos Coastal Basin
Segments: 1101, 1102

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Background and Goals

The Clear Creek watershed drains parts of Fort Bend, Harris, Brazoria, and Galveston Counties. In 1993, the Texas Department of State Health Services (DSHS; then known as TDH) issued a fish-consumption advisory for portions of Clear Creek due to elevated concentrations in fish tissue of the pesticide chlordane and of volatile organic compounds (VOCs addressed by another TMDL project). Because chlordane is a legacy pollutant — a chemical that has been banned or severely restricted, but which still remains in the environment — no significant new sources are expected to occur. The goal of this TMDL project is to reduce contaminant concentrations in fish tissue to levels that constitute an acceptable risk to consumers.

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TMDLs and Implementation Plan

The commission adopted these TMDLs on January 17, 2001. The EPA approved them on June 14, 2001, at which time they became part of the state’s Water Quality Management Plan.

The commission approved the I-plan on September 14, 2001.

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Status and Implementation

The consumption ban was rescinded in October 2001; the fish consumption use is no longer identified as impaired for chlordane. The DSHS assessment that resulted in a lifting of the consumption ban found that chlordane concentrations were actually higher in the fish tissue samples than they were in the previous assessment. However, the DSHS evaluates health risk based on the cumulative effect of all compounds detected. This value has been reduced to acceptable levels because the concentrations of the other legacy pollutants have declined.

In 2007, the TCEQ funded an assessment by DSHS of fish captured from the creek that verified that chlordane levels in fish remain at acceptable levels. Information on fish tissue advisories and bans in Texas can be found on the DSHS websiteExit the TCEQ.

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For More Information

For further information regarding this project, please e-mail us at and mention “Clear Creek chlordane” in the subject line. Or call us at 512-239-6682.

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