Lavaca Bay and Chocolate Bay: Evaluating Water Quality for Aquatic Life
Counties: Calhoun, Jackson, Victoria
Parameters: Mercury in water, dissolved oxygen
River and Coastal Basins: Bays and Estuaries, Lavaca River, Lavaca-Guadalupe Coastal Basin
Project Goals and Status
Lavaca Bay and Chocolate Bay, both included in Segment 2453, are part of the larger Matagorda Bay System located on the Texas Gulf Coast. Together these bays comprise 54.8 square miles. In both bays, water quality testing indicated that dissolved-oxygen concentrations and elevated mercury concentrations in the bays were not optimal for supporting aquatic life. People are advised to limit their consumption of fish and crabs from the bays because mercury concentrations in fish and crab tissue pose a risk to consumers. Oyster harvesting is restricted because of elevated bacteria concentrations.
This project addressed the concentrations of mercury and dissolved oxygen in the bays. Mercury, a metal, accumulates in the tissue of aquatic species and is toxic if consumed in large quantities over an extended period of time. 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 dissolved oxygen levels, which may harm fish and other aquatic organisms.
Sampling results for dissolved oxygen and mercury in water indicated that TDMLs are not necessary for those parameters. Based on those results, the TCEQ removed dissolved oxygen and mercury in water from the list of impairments for Lavaca Bay and Chocolate Bay in the Texas Water Quality Inventory and 303d List. Mercury in fish and crab tissue is being addressed by the Superfund Program. For more detailed project results, see the Project Overview or the final reports in the next section.
The final reports are available in PDF.
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