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Dallas and Tarrant Counties: A TMDL Project for Legacy Pollutants

A completed project to reduce legacy pollutant loads in streams and rivers in Dallas and Tarrant Counties. Together, the adopted total maximum daily load (TMDL) and the approved implementation plan (I-Plan) are the road map to improving water quality.

photo of lake worth
Lake Worth
Photograph courtesy of the Fort Worth Water Department
map of the Dallas and Tarrant counties legacy TMDL watersheds

Counties: Dallas, Tarrant
Parameters: chlordane, DDT, DDD, DDE, dieldrin, heptachlor epoxide, and polychlorinated biphenyls (PCBs) in fish tissue
Basin: Trinity River
Segments: 0805, 0841, 0841A

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Background and Goal

Seven legacy pollutants were detected in fish tissues in portions of the Upper Trinity River, the Lower West Fork Trinity River, and Mountain Creek Lake, all in the Dallas area. Legacy pollutants are chemicals whose use has been banned or severely restricted, but which still remain in the environment. The pollutants involved include chlordane, DDT, DDD, DDE, dieldrin, heptachlor epoxide, and PCBs, most of which were once used as insecticides.

TCEQ determines attainment of the fish consumption use based on risk analyses and consumption advisories conducted and published by the Texas Department of State Health Services (DSHS). The goal of this TMDL project is to reduce concentrations of fish-tissue contaminants to levels that are an acceptable risk to consumers.


All the pollutants for which TMDLs were adopted, with the exception of PCBs, have been reduced to acceptable levels. Legacy insecticides are no longer considered a risk to consumers of fish from these areas.

In August 2019, DSHS collected fish tissue samples at various sites on the Upper Trinity River. DSHS completed their updated risk analysis in 2021. Based on that analysis, DSHS has continued their Advisory 43, which recommends that consumers not eat any fish taken from the Upper Trinity River due to high concentrations of dioxin and PCBs in the fish tissue of all species. The advisory area includes the Clear Fork of the Trinity River from the Benbrook Reservoir Dam, the West Fork of the Trinity River from the Lake Worth Dam, and the main stem of the Trinity River downstream to the U.S. Highway 287 Bridge.

The DSHS 2021 analysis did not include Mountain Creek Lake. Their Advisory 59, issued in 2017, remains in effect, recommending that consumers not eat fish from the lake because of high concentrations of dioxin and PCBs. See more information about DSHS fish consumption advisories and bans on their map-based advisory viewer  or see the DSHS webpage about the types of fish consumption advisories and bans they issue.  

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Adopted TMDLs

The Commission adopted these TMDLs on December 20, 2000. The EPA approved these TMDLs on June 27, 2001, at which time they became part of the state's Water Quality Management Plan.

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Approved I-Plan

The Commission approved the I-Plan in August 2001.

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Contact the TMDL Program

Please email and mention the Dallas and Tarrant Counties TMDL project 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