EPA has published a draft document, Field‑Based Methods for Developing Aquatic Life Criteria for Specific Conductivity. Elevated water salinity, as measured by conductivity, has been shown to negatively affect aquatic life in freshwaters. Elevated conductivity is associated with multiple sources, including discharge from wastewater treatment facilities, surface mining, oil and gas exploration, runoff from urban areas, and discharge of agricultural irrigation return waters. The draft methods provide flexible approaches for developing science-based conductivity criteria for flowing waters that reflect ecoregional- or state-specific factors. Once final, states and authorized tribes located in any region of the country may use the methods to develop field-based conductivity criteria for flowing waters. This draft document provides a scientific assessment of ecological effects and is not a regulation. On December 23, 2016, EPA announced the availability of the draft document and opened a 60-day public review and comment period to solicit scientific views, data, and other information. In response to stakeholder requests, the comment period will be extended for an additional 62 days, from February 21, 2017 to April 24, 2017.

• Federal Register Notice: Extension of Public Comment Period: Draft Field-Based Methods for Developing Aquatic Life Criteria for Specific Conductivity (February 15, 2017)
• Federal Register Notice: Draft Field-Based Methods for Developing Aquatic Life Criteria for Specific Conductivity (December 23, 2016)
• Field Data Sets Used in the Draft Document (zip)(1 pg, 15 MB)

• Fact Sheet (PDF)(2 pp, 129 K, December 2016, EPA 822-F-07-005)
• Public Review Draft: Field-Based Methods for Developing Aquatic Life Criteria for Specific Conductivity (PDF)(215 pp, 5 MB, December 2016, EPA-822-R-07-010)
• Appendix A: Case Study I Supporting Materials (PDF)(49 pp, 1 MB)
• Appendix B: Case Study II Supporting Materials (PDF)(49 pp, 2 MB)
• Appendix C: Example Case for Estimation of Background Specific Conductivity (PDF)(37 pp, 2 MB)
• Appendix D: Development of a Background-to-Criterion Regression Model for Geographic Applicability (PDF)(32 pp, 852 K)
• Appendix E: Combined Data Set for Case Studies I and II (PDF)(81 pp, 19 MB)
• Appendix F: Case Example Using an Alternative Measure of Exposure ([HCO3− + SO42−]) (PDF)(56 pp, 2 MB)
• Appendix G: Case Example Using an Alternative Assessment Endpoint (Species of Fish) (PDF)(67 pp, 2 MB)
• 2015 External Peer Review Report (PDF)(74 pp, 685 K)
• EPA Response to 2015 External Peer Review Report (PDF)(51 pp, 379 K)
• 2014 External Peer Review Report (PDF)(194 pp, 2 MB)
• EPA Response to 2014 External Peer Review Report (PDF)(160 pp, 1 MB)