STRESSOR IDENTIFICATION GUIDANCE DOCUMENT U.S. Environmental Protection Agency Office of Water Washington, DC 20460 Office of Research and Development Washington, DC 20460 EPA-822-B-00-025 December 2000 Disclaimer This Stressor Identification Guidance Document provides guidance to assist EPA Regions, States, and Tribes in their efforts to protect the biological integrity of the Nation’s waters, one of the primary objectives of the Clean Water Act (CWA). It also provides guidance to the public and the regulated community on identifying stressors that cause biological impairment. While this document constitutes the U.S. Environmental Protection Agency’s (EPA’s) scientific recommendations regarding stressor identification, this document does not substitute for the CWA or EPA’s regulations, nor is it a regulation itself. Thus, it cannot impose legally binding requirements on EPA, States, Tribes, or the regulated community, and may not apply to a particular situation based upon the circumstances. When appropriate, State and Tribal decisionmakers retain the discretion to adopt approaches on a case-by-case basis that differ from this guidance. EPA may change this guidance in the future. Stressor Identification Guidance Document Acknowledgments Primary Authors: EPA, Office of Research and Development: Susan Cormier, Ph.D. Susan Braen Norton, Ph.D. Glenn Suter II, Ph.D. EPA, Office of Science and Technology: Donna Reed-Judkins, Ph.D. Contributing Authors: EPA, Office of Science and Technology: Jennifer Mitchell William Swietlik Marjorie Coombs Wellman EPA, Office of Wetlands, Oceans and Watersheds: Thomas Danielson Chris Faulkner Laura Gabanski, Ph.D. Molly Whitworth, Ph.D. EPA, Office of Research and Development: Edith Lin, Ph. D. Bhagya Subramanian EPA, Office of Enforcement and Compliance Assurance Brad Mahanes Other Affiliations: David Altfater, Ohio Environmental Protection Agency William Clements, Ph.D., Colorado State University, Fort Collins, Colorado Susan P. Davies, Ph.D., Maine Department of Environmental Protection, Augusta, Maine Jeroen Gerritsen, Ph.D., Tetra Tech, Owings Mills, Maryland Martina Keefe, Tetra Tech, Owings Mills, Maryland Sandy Page, Tetra Tech, Owings Mills, Maryland Jeffrey Stinson, Ph.D., U.S. Air Force Technical Editors: EPA, Office of Research and Development, National Risk Management and Restoration Lab: Jean Dye, Ph.D. Scott Minamyer iii Stressor Identification Guidance Document Tetra Tech: Abby Markowitz Sandra Page Colin Hill Brenda Fowler Stressor Identification and Evaluation Workgroup Members: Co-leads: Office of Water: Donna Reed-Judkins, Ph.D., Office of Science and Technology Office of Research and Development: Susan Cormier, Ph.D., National Exposure Research Lab Members: Office of Water: Office of Science and Technology: Tom Gardner, Susan Jackson, Jennifer Mitchell, Keith Sappington, Treda Smith, William Swietlik, Brian Thompson, Marjorie Wellman Office of Wetlands, Oceans, and Watersheds: Thomas Danielson, Laura Gabanski, Chris Faulkner, Molly Whitworth, Ph.D. Office of Research and Development: National Center for Environmental Assessment: Susan Norton, Ph.D., Glenn Suter II, Ph.D. National Health and Environmental Effects Laboratory: Naomi Detenbeck, Ph.D., Wayne Munns, Ph.D. National Risk Management and Restoration Laboratory: Alan Everson, Scott Minamyer Office of Enforcement and Compliance Assurance Brad Mahanes EPA Regions Toney Ott, Region 8 Other Federal Agencies: Jeffrey Stinson, Ph.D., U.S. Air Force States: Susan Davies, Maine Department of Environmental Protection, Augusta, Maine Chris O. Yoder, Ohio EPA, Columbus, Ohio Other Supporting EPA Members: Don Brady, Alan Hais, Margarete Heber, Mary Sullivan Contract Support, Tetra Tech, Owings Mills, Maryland: Michael Barbour, Ph.D., Jeroen Gerritsen, Ph.D., Martina Keefe, Sandy Page iv Stressor Identification Guidance Document Peer Reviewers: A. Fred Holland, Ph.D., Director, Marine Resources Research Institute of South Carolina. Kent Thornton, Ph.D., FTN Associates Wayne Landis, Ph.D., Director, Institute of Environment Toxicology and Chemistry, Western Washington University The authors wish to gratefully acknowledge all others, not named above, who helped to prepare this document. The sum of these efforts contributed to the success of this guidance. Special thanks also to all the EPA and State scientists who participated in the video conference in October, 1999; the Region III Mid-Atlantic Water Pollution Biology Workshop at Cacapon, West Virginia, in March 2000; and the Biological Advisory Committee meeting in Cincinnati, in May, 2000. Comments were also provided by a number of EPA scientists and regulators and by other stakeholders, including the Kansas Department of Health and Environment, Arizona Department of Environmental Quality, Denver Metro Wastewater Reclamation District, Pennsylvania Department of Environmental Protection, Proctor and Gamble, The Nature Conservancy, and the U.S. Geological Survey. Comments from the workshops and other commenters helped shape the guidance. The cover illustration was provided by a fifth grade student at Ursula Villa Elementary School, Mount Lookout, OH. According to the illustrator, the front cover is the river when you first pick up this book, and the back cover is the river after you’ve followed the instructions. v Stressor Identification Guidance Document Table of Contents Acknowledgments .....................................................iii Acronym List ........................................................xiii Executive Summary ES.1 The Clean Water Act, Biological Integrity, and Stressor Identification............................................ ES-1 ES.2 Intended Audience........................................ ES-2 ES.3 Applications of the SI Process .............................. ES-2 ES.4 Document Overview...................................... ES-3 Chapter 1: Introduction to the Stressor Identification (SI) Process 1.1 Introduction ...............................................1-1 1.2 Scope of this Guidance ......................................1-2 1.3 Data Quality Issues .........................................1-2 1.4 Overview of the SI Process ...................................1-3 1.4.1 The SI Process ........................................1-3 1.4.2 SI Process Iterations ....................................1-5 1.4.3 Using the Results of Stressor Identification ..................1-5 1.5 Use of the SI Process in Water Quality Management Programs ......1-6 Chapter 2: Listing Candidate Causes 2.1 Introduction ...............................................2-1 2.2 Describe the Impairment .....................................2-1 2.3 Define the Scope of the Investigation...........................2-3 2.4 Make the List .............................................2-4 2.5 Develop Conceptual Models..................................2-5 Chapter 3: Analyzing the Evidence 3.1 Introduction ...............................................3-1 3.2 Associations Between Measurements of Candidate Causes and Effects...................................................3-2 3.3 Using Effects Data from Elsewhere ............................3-6 3.4 Measurements Associated with the Causal Mechanism .............3-9 3.5 Associations of Effects with Mitigation or Manipulation of Causes . 3-10 Chapter 4: Characterizing Causes 4.1 Introduction ................................................4-1 4.2 Methods for Causal Characterization ............................4-1 4.2.1 Eliminating Alternatives .................................4-3 4.2.2 Diagnostic Protocols or Keys .............................4-7 4.2.3 Strength of Evidence Analysis ............................4-8 4.2.3.1 Causal Considerations for Strength of Evidence Analysis......................................4-9 4.2.3.2 Matching Evidence with Causal Considerations ......4-14 4.2.3.3 Weighing Causal Considerations ..................4-14 4.3 Identify Probable Cause and Evaluate Confidence ................4-17 vii Stressor Identification Guidance Document Table of Contents (continued) Chapter 5: Iteration Options 5.1Reconsider the Impairment ....................................5-1 5.2Collect More Information on Previous and Additional Scenarios.......5-2 Chapter 6: Presumpscot River, Maine 6.1 Executive Summary ........................................6-1 6.2 Background ...............................................6-3 6.3 List Candidate Causes.......................................6-5 6.4 Analyze Evidence and Characterize Causes: Eliminate ............6-8 6.5 Analyze Evidence and Characterize Causes: Strength of Evidence . 6-11 6.6 Characterize Causes: Identify Probable Cause ..................6-17 6.7 Significance and Use of Results..............................6-18 6.8 References...............................................6-18 Chapter 7: Little Scioto River, Ohio 7.1 Executive Summary ........................................7-1 7.2 Introduction ...............................................7-4 7.3 Evidence of Impairment .....................................7-5 7.4 List Candidate Causes......................................7-10 7.5 Analyze Evidence to Eliminate Alternatives ....................7-13 7.5.1 Data Analyzed .......................................7-13 7.5.2 Associations between Candidate Causes and Effects .........7-14 7.5.3 Measurements Associated with the Causal Mechanism: Exposure Pathways ...................................7-24 7.5.4 Summary of Analyses for Elimination .....................7-26 7.6 Characterize Causes: Eliminate