Clear Creek: A TMDL Project for Chlordane
Clear Creek Above Tidal
Counties: Brazoria, Fort Bend, Galveston, and Harris
River Basin: San Jacinto–Brazos Coastal Basin
Segments: 1101, 1102
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.
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.
- Two Total Maximum Daily Loads for
Chlordane in Clear Creek
- Response to Public Comment on the Clear Creek TMDLs
The commission approved the implementation plan on September 14, 2001.
- Implementation Plan for Clear Creek Chlordane TMDLs
- Response to Public Comment on the Clear Creek Implementation Plan
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The consumption ban was rescinded in October 2001; the fish consumption use is no longer identified as impaired for chlordane.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 website .
For More Information
For further information regarding this project, please e-mail us at firstname.lastname@example.org and reference “Clear Creek chlordane” in the subject line. Or call us at 512-239-6682.