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Nueces Bay: A TMDL Project for Zinc

A project to develop and implement a TMDL to reduce zinc in oyster harvesting waters. The TMDL is completed and the I-Plan is approved.

photo of Nueces Bay
Nueces Bay

Counties: Nueces, San Patricio
Parameter: Zinc in oyster tissue
Basins: Bays and Estuaries, San Antonio–Nueces Coastal, Nueces River, Nueces–Rio Grande Coastal
Segment: 2482

On this page:

Background and Goals

Nueces Bay is a shallow, secondary bay that receives freshwater from the Nueces River and exchanges saline water with Corpus Christi Bay. Economic activities in and around the bay include petrochemical refining and production, agriculture, manufacturing, recreation, maritime commerce, and tourism. Ecologically, Nueces Bay provides a home for many plants and animals, and plays a role in water purification and storm protection.

Harvesting of oysters and other edible shellfish from the bay is currently restricted because concentrations of zinc in oyster tissue pose a risk to consumers. The TCEQ’s Total Maximum Daily Load (TMDL) Program is directing a project to reduce zinc concentrations to levels that make it safe to harvest and eat oysters from the bay.

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Public Participation

The TMDL Program worked with the existing forum of the Coastal Bend Bays and Estuaries Program (CBBEP)Exit the TCEQ to involve area stakeholders in the TMDL project.

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The commission adopted this TMDL on November 1, 2006. It was approved by the EPA on December 15, 2006, at which time it became part of the state's Water Quality Management Plan.

Updates to TMDLs

From time to time, it is necessary to revise TMDLs to account for changing conditions in the watershed, such as new or amended permits, or urban growth, or to correct oversights in the original TMDL report. Revisions to the load allocations in TMDLs are made via the state’s Water Quality Management Plan (WQMP), which is updated quarterly.

The WQMP provides projected effluent limits for use in planning and permitting activities under the Texas Pollutant Discharge Elimination System (TPDES). The TCEQ reviews all applications for new and amended permits for conformance with applicable portions of the WQMP, including adopted TMDLs.

Revisions to the TMDL are documented in the approved WQMP updates listed below.

Learn more about WQMP updates and about opportunities to comment on revisions to them.

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Implementation Plan

The commission approved the I-Plan on October 24, 2007.

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Technical Support Document

Annual Reports

Miscellaneous Reports

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For More Information

Please send an e-mail to, and reference the Nueces Bay 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