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Assessing Toxicity in Ambient Water and Sediment in Seven Texas Water Bodies

A completed project to assess the extent and severity of toxicity in ambient water and sediment in seven Texas water bodies.
photo of Alligator Bayou
Alligator Bayou

Counties: Brazos, Brewster, Cameron, Harris, Jefferson, Kinney, Maverick, Presidio, Terrell, Val Verde, Webb, Willacy, Zapata
Parameter: Toxicity in water and sediment
Basins: Neches-Trinity Coastal, San Jacinto River, Brazos River, Nueces–Rio Grande Coastal, Rio Grande
Segments: 0702A, 1007A, 1209A, 1209B, 2201, 2304, 2306

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Background and Goals

Water quality data assessed in 1999 indicated that toxic conditions might exist in the water or the sediment of seven water bodies at various locations in Texas. Toxicity in water and sediment are conditions that are measured to determine if a water body can support a healthy aquatic community.

To determine the potential of water bodies to be toxic to aquatic life, sensitive aquatic organisms are exposed to water and sediment samples under laboratory conditions. These sensitive organisms serve as surrogates for the species indigenous to the water body being tested. However, there is not always a positive correlation between toxicity observed in the laboratory and actual toxic conditions in the water body being tested. Also, the laboratory tests used to determine the potential for toxicity do not identify the specific chemical toxicants responsible for the observed effects.

The goal of this project was to confirm the presence of toxicity and to determine its causes, where present. Summaries of the results for each water body assessed during the project are provided below.

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These summaries are provided in PDF.

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Final Reports

These reports are provided in PDF.

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These posters were presented at the SETAC 24th Annual Meeting in North America, November 2003. They are provided in PDF.

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For More Information

For more information about the the project, please e-mail us at, and reference the Toxicity Assessment 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