United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Research Abstract Government Performance Results Act Goal: Sound Science Significant Research Findings: Stressor Identification Guidance State and Tribal water quality experts are finding water bodies where the fish, invertebrate, algae or plant communities (or other aquatic life) have been detrimentally impacted by different single or multiple causes. In many cases, the cause, or causes, of these biological impairments have not yet been identified. The Stressor Identification Guidance Document is designed to assist water quality managers in identifying unknown causes of biological impairments in any type of water body. Scientifically sound identification of the cause of water quality impairment is an initial step in developing Total Maximum Daily Loads (TMDLs), as required by Section 303(d) of the Clean Water Act (CWA). The Stressor Identification Guidance Document was published under the authority of Section 304(a)(2) of the CWA. Research Approach The Stressor Identification Guidance Document provides a logical, scientific process by which State, Tribal, and other water quality experts can evaluate available information to identify the stressor(s) causing biological impairments. A step-wise analytical process was developed to determine the cause of an ecological impairment. Logic steps in the causal identification process were derived from the scientific literature including the areas of eco-epidemiology, human epidemiology, forensics, symptomology, diagnosis, and general philosophy of science and inductive inference. The three main steps of the stressor identification process are (1) list candidate causes of impairment, (2) analyze the evidence, and (3) characterize the causes. The last step, characterizing the cause, evaluates the evidence in three steps: elimination, diagnosis, and strength of evidence. When evidence is adequate, investigators should be able to use this guidance to successfully identify the likely cause(s). This guidance will also help investigators identify where evidence is weak or lacking and needs to be developed to enable successful identification of the stressor(s). Scientific Problem and Policy Issues Results and Implications National Exposure Research Laboratory — October 2001 ------- Once the causes of the biological impairments are identified, water resource managers will be better able to locate the sources of the stressor(s) and take management actions aimed at improving the biological condition of the water body. This guidance is advisory in nature and its use is not mandatory. As such this guidance does not impose legally-binding requirements on the U.S. EPA, the States, Tribes, industry, the public, or any other entity. The U.S. EPA has published the Stressor Identification Guidance Document under document number EPA-822-B-00-025, dated December 2000. Paper copies can be obtained from the U.S. EPA Water Resource Center by phone at (202) 260-7786, by e-mail at center.water-resource@epa.gov. or through conventional mail by sending a letter of request to U.S. EPA Water Resource Center, Ariel Rios Building, 1200 Pennsylvania Ave., Washington, DC 20460. Copies of the document may also be obtained from the U.S. EPA National Center for Environmental Publications and Information (NCEPI) by phone at (513) 489-8190 or through conventional mail at 11029 Kenwood Road, Cincinnati, OH 45242. The document and fact sheet are also available on the U.S. EPA website at http://www.epa.gov/OST/biocriteria. Future Research Several avenues of research continue to build on the foundation established by the stressor identification process. Case studies are being performed to demonstrate how the process works with both simple and complex situations in a variety of ecosystems. Associations and other types of evidence are being developed that can be used in many causal analyses, for instance, the relationship between excessive nutrients and sensitive biological endpoints such as aquatic insects. This type of information can be used in many causal determinations. A Causal Analysis, Diagnosis and Decision Information System (CADDIS) is being planned that will allow routine application of the process and put needed data and tools at the fingertips of resource managers. Research Collaboration and Publications National Exposure Research Laboratory — October 2001 ------- Contacts for Questions and inquiries can be directed to: Additional Information Susan Cormier U.S. EPA, Office of Research and Development National Exposure Research Laboratory 26 W. Martin Luther King Dr. Cincinnati, OH 45268 Phone: 513/569-7995 E-mail: cormier.susan@epa.gov National Exposure Research Laboratory — October 2001 ------- |