Case Study Demonstrating the Stressor Identification Process That Identifies Causes of Biological Impairment in the Nation's Water Bodies

Objective/Intended Use

The stressor identification (SI) program is developing guidance for the determination of the causes of impairment in aquatic ecosystems. This project produces a case study of the application of the SI that will serve to inform the development of the SI technical support system and will serve as an example for users.

The SI methodology is essential to the implementation of TMDLs, to the use of bioassessment in the NPDES program, and other instances of assessment of impaired communities. The development of the methodology has depended on a workgroup of individuals from OW, the regions, other federal agencies, and the states. Because of the complexity and unfamiliarity of the methodology, these users and others have asked for case studies that demonstrate the use of the method in contexts that are relevant to their uses. In addition, they have asked for technical support which will be developed under another project, but which will require case studies and SI tools to ensure its realism and utility.

Abstract

The stressor identification program developed guidance for identifying the causes of biological impairments in the nation's waters:

U.S. EPA. 2000. Stressor identification guidance document. EPA/822/B-00/025. U.S. Environmental Protection Agency, Washington, DC.

The methodology for causal analysis and a case study have been published in a peer-reviewed journal:

Suter, G.W. II., S.B. Norton and S. Cormier. 2002. A method for inferring the causes of observed impairments in aquatic ecosystems. Environ. Toxicol. Chem. 21:1101-1111.

Norton, S.B., S.M. Cormier, G.W. Suter II, B. Subramanian, E. Lin, D. Altfater, and B. Counts. 2002. Determining the causes of impairment in the Little Scioto River, Ohio: Part I. Listing Candidate Causes and Analyzing Evidence. Environ. Toxicol. Chem. 21:1112-1124.

Cormier, S.M., S.B. Norton, G.W. Suter II, D. Altfater, and B. Counts. 2002. Determining the causes of impairment in the Little Scioto River, Ohio: Part II. Characterization of Causes. Environ. Toxicol. Chem. 21:1125-1137.

This project developed another case study to demonstrate the application of the methodology to a different situation with different stressors.

Project Status

The project is proceeding as planned. The team has multiple case studies in various states of development including an urban watershed in Maine and a suburban watershed in Maryland. One will be chosen to meet the APM.

Project Start Date

10/01/2002

Project Completion Date (Actual/Projected)

09/30/2003