Ecological Screening-Level Risk Assessment of the Lower Ottawa River
 

The Ottawa River Risk Assessment project was started in late 1999 as a partnership between Toledo Metropolitan Area Council of Governments (TMACOG), Ohio EPA, and the Maumee RAP. It was completed in November 2001. Since 1987 when the RAP was established, businesses and governmental agencies have invested millions of dollars to identify and remediate sources of pollution going into the Ottawa River in Toledo. With those sources removed, the next step in restoration of the river is with the sediments.

The project was administered by TMACOG in conjunction with other agencies of the Ottawa River Remediation Team (ORRT). These include Ohio EPA, Ohio Department of Health, US Fish & Wildlife Service, and the City of Toledo. This team, through a competitive process, selected Limno Tech Inc of Ann Arbor as its prime contractor to prepare the Risk Assessments. Limno Tech in turn subcontracted the Human Health Assessment to Intertox and the Ecologic Risk Assessment to Parametrix.

An ecological screening-level risk assessment (SLRA) of the lower Ottawa River was conducted as an initial effort to prioritize chemical hot spots for possible remediation. The SLRA followed the U.S. EPA’s standard ecological risk assessment guidelines and included the following sections:

1. Problem Formulation;
2. Exposure Characterization;
3. Effects Characterization; and
4. Risk Characterization.

The Problem Formulation stated the goals of the SLRA, described the study area, and identified the ecological receptors evaluated. The Exposure Characterization described the chemistry data available and the methods for quantifying exposure of ecological receptors to chemicals. The Effects Characterization presented the Toxicity Reference Values (TRVs) used for comparison to the chemical exposure levels. Lastly, the Risk Characterization compared the Exposure and Effects Characterization results to estimate whether ecological receptors are at risk from chemicals in the lower Ottawa. Multiple lines of evidence were included in the Risk Characterization to provide an overall weight-of-evidence.

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