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LINKING GREAT WATERSHEDS AND RIVERS TO FORECAST THE IMPACT OF CONTAMINANT STRESSORS ON LARGE RECEIVING WATERS
Citation:
Rossmann, R., W. L. Richardson, K R. Rygwelski, AND R G. Kreis. LINKING GREAT WATERSHEDS AND RIVERS TO FORECAST THE IMPACT OF CONTAMINANT STRESSORS ON LARGE RECEIVING WATERS. Presented at US EPA Science Forum 2002 Meeting: Meeting the Challenges, Washington, DC, May 1-2, 2002.
Description:
Contaminated sediments are pervasive within the waters of the nation. A number of contaminants are bioaccumulative and are an unacceptable risk to the ecosystem, including humans. Many sites having contaminated sediments are contained within state 305(b) and 303(d) listings and will require establishment of Total Maximum Daily Loads (TMDLs). There is no national construct for dealing with contaminated sediments and their remediation.
Mass balance mathematical models are being developed, calibrated, verified, and applied to Great Watersheds and Rivers to 1) support decision makers with determining future management options by comprehensively evaluating the relative loading rates by media, forecasting contaminant concentrations in biota, sediment, and water for different remediation scenarios, and forecasting environmental benefits of specific load reduction alternatives; 2) demonstrate development of TMDLs by linking watersheds to large receiving water bodies, and 3) predict contaminant-induced biotic effects for various components of the ecosystem.
Mass balance models have provided the foundation for actions under EPA Superfund and USFWS Natural Resource Damage Assessment programs. This approach has withstood an aggressive challenge from responsible parties to emerge as the primary forecasting tool of environmental conditions. Specifically the model construct has been used for the WI Dept. of Natural Resources, Green Bay, WI receiving body of water. Because the majority of PCBs are derived from sediments contaminated by past industrial practices and fish consumption advisories exist for PCBs, remediation of the sediments is necessary. These findings have led EPA Superfund and WI DNR to investigate various alternatives of remediation. For the most rigorous remediation scenario, the FDA action level of 2 ppm PCBs in fish for human consumption can be obtained in about 10 years after remediationis completed. Without remediation, the goal cannot be achieved for 90 years.
A similar approach is being applied to Lake Michigan in support of the Lake Michigan Lakewide Management Plan and Superfund Strategies for contaminated sediments. Because they bioaccumulate, a major issue is PCBs. Though fish currently meet the FDA action level of 2 ppm, they do not meet the Great Lakes Sport Fish Consumption Advisory goal of 0.05 ppm for unlimited consumption or the goal of 0.023 ppm to protect mink (most sensitive species). The tributaries and the atmosphere contribute similar loads of PCBs to the main lake with considerable recycling of loads from the lake's sediments. There is also a large net volitilization flux loss of PCBs from the lake to the atmosphere. Atrazine is not exected to be a problem with respect to current standards applicable to Lake Michigan. As modeling progresses an approach to establish TMDLs will be demonstrated for Lake Michigan using PCBs, atrazine, mercury, and other selected parameters.
This abstract does not necessarily reflect EPA policy.