Conceptual Models for Watershed and Regional Assessments

To provide guidance and tools for ecological risk assesors.

Project Status

The project was restarted with a new focus and new EPA lead in 2001. A draft report on examples of conceptual models and how to use them has been through internal EPA review.
A final report including conceptual model interview results and EPA comments is expected in June 2005.

Project Start Date



Conceptual models, as defined here, describe and illustrate the relationships between ecological receptors, the stressors to which they may be exposed, and the potential sources of the those stressors within a particular area or ecosystem. This document describes conceptual models and how they are developed, their value in environmental management, and provides guidance and examples of how they can be used by watershed and regional ecological assesors. By clarifying causal relationships they lay a foundation for subsequent research, analysis and environmental management. They also serve as a communication tool, help focus analyses, identify important data gaps and track the progress of the risk assessment. The elements of a conceptual model are presented. The processes followed by several watershed and regional scale assesors are described. A detailed example of the model developed for Big Darby Creek watershed is also provided. As of October 2005, external peer review comments on the report are being evaluated.

Related Links

Future Products

  • Regional Ecological Assessment Methods