Application of Watershed Ecological Risk Assessment Methods To Watershed Management

Abstract

Watersheds are frequently used to study and manage environmental resources because hydrologic boundaries define the flow of contaminants and other stressors. Ecological assessments of watersheds are complex because watersheds typically overlap multiple jurisdictional boundaries, are subjected to multiple environmental stressors, and have multiple stakeholders with diverse environmental and socioeconomic interests. Ecological risk assessment (ERA) is an approach that has successfully been used to increase the use of ecological science in decision making, by evaluating the likelihood that adverse ecological effects may result from exposure to one or more stressors, yet its application to watershed assessment is limited. This report supplements the Guidelines for Ecological Risk Assessmentby addressing issues commonly encountered when conducting watershed ecological assessments. Suggestions and examples to follow are provided based upon lessons learned from prior watershed ERAs. This report is of potential use to ecologists, hydrologists, watershed managers, risk assessors, landscape ecologists, and other scientists and managers seeking to increase the use of environmental assessment data in decision making. Each activity and phase of the watershed ERA process is explained sequentially in this report. Guidance on how to involve stakeholders to generate environmental management goals and objectives is provided. The processes for selecting assessment endpoints, developing conceptual models, and selecting the exposure and effects pathways to be analyzed are described. Suggestions for predicting how multiple sources and stressors affect assessment endpoints are also provided; these include using multivariate analyses to compare land use with biotic measurements. In addition, the report suggests how to estimate, describe, and communicate risk and how to evaluate management alternatives.
A watershed approach is frequently used to study and manage environmental resources. Ecological risk assessment (ERA) is a process for analyzing environmental problems and is intended to increase the use of ecological science in decision making in order to evaluate the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors. Applying ERA principles at the watershed scale makes scientific information more relevant to the needs of environmental managers. Watershed ERAs are complex because addressing impacts from multiple sources and stressors on multiple endpoints presents a scientific challenge and because multiple stakeholders have diverse interests. The needs of managers and stakeholders may change, and the need to take action may require using the best available information at the time, sometimes before an ERA is completed. Therefore, at the watershed scale, flexibility on how to implement the ERA process is necessary. It is also important that risk assessors and managers interact regularly and repeatedly.

Each activity and phase of the watershed ERA process is explained sequentially in this report. Guidance on how to involve stakeholders to generate environmental management goals and objectives is provided. The processes for selecting assessment endpoints, developing conceptual models, and selecting the exposure and effects pathways to be analyzed are described. Suggestions for predicting how multiple sources and stressors affect assessment endpoints are also provided; these include using multivariate analyses to compare land use with biotic measurements. In addition, the report suggests how to estimate, describe, and communicate risk and how to evaluate management alternatives.

Impact/Purpose

The purpose of this EPA report is to provide suggestions and examples for making scientific information more relevant to the needs of watershed managers by using ERA principles to help structure ecological assessments of watersheds.

Status

This is the final report. The National Center for Environmental Assessment is currently determining the cause of biological impairments in watersheds through the Causal Analysis/Diagnosis Decision Information System (CADDIS) - http://cfpub.epa.gov/caddis/

Citation

U.S. EPA. Application of Watershed Ecological Risk Assessment Methods To Watershed Management. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-06/037F (NTIS PB2008-104486), 2008.

Date	Description
01- 1993	EPA's Office of Water, Office of Research and Development, and the Risk Assessment Forum agree to co-sponsor five watershed assessments.
02- 1997	Science Advisory Board Review of planning and problem formulation reports which were completed for all five watersheds.
03- 1998	EPA's Guidelines for Ecological Risk Assessment were developed in part - based on lessons learned from the five watershed assessments
04- 2000	EPA released a workshop report on characterizing ecological risk at the watershed scale.
05- 2000	EPA released the report, Gathering information for watershed ecological risk assessments: A review of ten watershed assessments
06- 2001	Journal article published, Identifying sources of stress to native aquatic fauna using a watershed ecological risk assessment framework.
07- 2002	EPA annouces the release of the Watershed ecological risk assessment training module (Watershed Academy).
08- 2002	Journal article published, Applying ecological risk assessment principles to watershed assessment and management.
09- 2002	EPA releases the report, Clinch and Powell Valley watershed ecological risk assessment.
10- 2002	EPA releases the report, Ecological risk assessment for the Middle Snake River, Idaho.
11- 2002	EPA releases the report, Waquoit Bay watershed ecological risk assessment: The effect of land-derived nitrogen loads on estuarine eutrophication.
12- 2002	Journal article published, Diagnosing causes of native fish and mussel species decline in the Clinch and Powell River Watershed, Virginia, USA.
13- 2004	Journal article published, Using ecological risk assessment to identify the major anthropogenic stressor in the Waquoit Bay watershed, Cape Cod, Massachusetts.
14- 2007	Journal article published, Using ecological risk principles in a source water protection assessment .
15- 2007	Journal article published, The Integration of ecological risk assessment and structured decision making into watershed management.

• Application of Watershed Ecological Risk Assessment Methods to Watershed Management (Final) (PDF)  (83  pp, 548.8 KB, about PDF)

Related Link(s)

• WATERSHED AND OTHER PLACE-BASED RISK ASSESSMENTS