As ecological risk assessment evolves, it is moving beyond focus on single species toward addressing multiple species and their interactions, and from assessing effects of simple chemical toxicity to the cumulative impacts of multiple interacting chemical, physical, and biological stressors. While EPA and others have developed guidance and have considerable experience in applying the ecological risk assessment paradigm in specific-based approaches (such as those focused on particular chemical contaminates), specific guidance for using it in place-based approaches (such as those conducted on a watershed-wide scale) is still limited.

One of the principal challenges in applying ecological risk assessment to watershed management and decision making is the need for a framework for characterizing risks that involve numerous stressors, interconnected pathways, multiple endpoints. To develop the needed guidance in this area a workshop was held that gathered 35 participants with extensive experience in relevant disciplines such as watershed ecological assessment, ecological risk assessment, watershed management, or regional-scale assessment. To focus workshop discussions, several charge questions addressing the issues of greatest concern for characterizing risk at the watershed scale were developed prior to the workshop. This report provides the proceedings from the workshop and includes an introduction, a synthesis of discussion and recommendations, and summaries of presentations and breakout sessions.



This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.