Groundwater to Surface Water Evaluation, Patrick Bayou
Integral is currently evaluating potential groundwater contributions to sediment toxicity in an urban estuary in Texas. Because the water body is listed as impaired under the Clean Water Act, more stringent regulatory restrictions were required for groundwater discharges unless it could be shown that groundwater was not an important contributor to the sediment toxicity.
Using existing data, Integral developed a weight-of-evidence (WOE) evaluation approach to assess the question regarding sediment toxicity. The evaluation consists of various lines of evidence, including 1) similarities in chemical signatures in groundwater and sediment, 2) relative chemical mass loading from groundwater compared to other upland and in-water sources, 3) spatial analysis of sediment toxicity data in relation to groundwater discharge and loading, and 4) risk and causation analyses. The WOE evaluation is being performed in concert with multiple stakeholders and communicated in a workgroup setting to state and federal regulators. A variety of statistical, hydrological, toxicological, and forensic analyses is being used to evaluate whether groundwater is the cause of observed sediment toxicity in the bayou.
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