TMDL for Temperature in the Columbia and Lower Snake Rivers
Summary
On May 18, 2020, EPA established the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load (TMDL) as required by Section 303(d) of the Clean Water Act and its implementing regulations (Title 40 of the Code of Federal Regulations, Section 130.7).
Spanning almost 900 river miles, the TMDL examines sources of temperature impairments on the Columbia River from the Canadian border to the Pacific Ocean, and on the lower Snake River in Washington from its confluence with the Clearwater River at the Idaho border to its confluence with the Columbia River.
The TMDL is required under the federal Clean Water Act because significant portions of the Columbia and lower Snake Rivers are identified by the states of Washington and Oregon as impaired due to temperatures that exceed the numeric criteria portion of the states’ water quality standards at various locations and times of year.
EPA accepted public comments on the TMDL from May 21 through August 20, 2020. TMDL program regulations require that EPA consider comments, make necessary changes, and transmit the re-issued TMDL to the states for incorporation into their Water Quality Management Plans.
On August 13, 2021, EPA transmitted the re-issued TMDL to the states of Oregon and Washington.
The TMDL document, EPA's responses to public comments, and appendices are available below.
For more information, contact John Palmer ([email protected]).
Documents
Note: Appendices A, C, F and G did not change from the 2020 TMDL. Appendices B, D, E, H, and I were updated to reflect changes in the reissued TMDL. Appendix J is new.
- Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load (TMDL) (pdf)
- Erratum for the Columbia and Lower Snake Rivers Temperature TMDL (pdf)
- Response to Public Comments on Columbia and Lower Snake Rivers Temperature TMDL (pdf)
- Appendix A: Temperature Water Quality Standards for the Columbia and Lower Snake Rivers (pdf)
- Appendix B: Temperature Data Compilation, Quality Assurance and Analysis (pdf)
- Appendix C: RBM10 Model Development Report (pdf)
- Appendix D: RBM10 Model Scenario Report (pdf)
- Appendix E: Tributary Assessment Methods and Results (pdf)
- Appendix F: ORD Technical Memorandum on Tributary Restoration (pdf)
- Appendix G: Climate Change (pdf)
- Appendix H: Temperature Metric Analysis (pdf)
- Appendix I: Temperature Heat Loads (pdf)
- Appendix J: Considerations for Permit Writers on Wasteload Allocations (pdf)