STRESSOR IDENTIFICATION GUIDANCE DOCUMENT

1,95

MB

228

stron

5914

ID

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

2001

rok

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

Chapter 5: Iteration Options

5.1 Reconsider the Impairment 5-1

5.2 Collect 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 7-26

7.7 Analyze Evidence for Diagnosis 7-28

7.8 Analyze Evidence to Compare Strength of Evidence 7-28

7.9 Characterize Causes: Strength of Evidence . 7-31

7.10 Characterize Causes: Identify Probable Cause 7-47

7.11 Discussion . 7-48

7.12 References . 7-50

7.13 Additional Tables . 7-54

APPENDICES

A Overview of Water Management Programs Supported by the SI

B Worksheet Model

C Glossary of Terms

D Literature Cited

INDEX