Umpqua River Basin Temperature TMDL

On this page:

• Summary
• TMDL documents
• Public comments
• Contacts

Project summary

The Umpqua River Basin is comprised of three major rivers – the North Umpqua, South Umpqua, and the Umpqua. These rivers, and numerous tributaries, are identified on the 2022 Oregon Clean Water Act section 303(d) list of impaired waters because of elevated temperature.

Temperature influences critical biological processes for aquatic life, such as survival, growth, reproduction, and behavior. Elevated water temperatures are harmful to aquatic life, particularly salmonid fishes such as salmon and steelhead.

The Clean Water Act requires the development of TMDLs to restore impaired waters to fully support their beneficial uses, such as fish spawning, rearing, migration, and cold water habitat.

A TMDL – sometimes called a water quality restoration plan – is the calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet water quality standards for that particular pollutant over time.

The Umpqua River Basin TMDL aims to restore water quality conditions and protect aquatic life by determining the allowable amount of heat from sources in the watershed.

EPA developed the TMDL to fulfill a court ordered requirement. The U.S. District Court for the District of Oregon ordered the Oregon Department of Environmental Quality and EPA to replace previously approved temperature TMDLs because of a change in applicable water quality criteria. The 2025 Umpqua Basin Temperature TMDL replaces the 2006 Umpqua Basin Temperature TMDLs.

The TMDL was required to be completed no later than June 28, 2025.

Additional information about this project is available on the State of Oregon's website at Temperature TMDL Replacement: Umpqua River Basin.

To learn more about TMDLs, visit Overview of Total Maximum Daily Loads.

TMDL documents

• Umpqua River Basin TMDL for Temperature (pdf) (7.91 MB, June 27, 2025)
  Final TMDL (not including appendices).
  • Appendix A: Current Conditions (pdf) (4.53 MB)
    Current temperature conditions in the Umpqua, North Umpqua and South Umpqua River Basins within the geographic scope of the TMDL project.
  • Appendix B: Seasonal Variation and Critical Conditions (pdf) (1.78 MB)
    Seasonal variation and temperature critical conditions for the Umpqua River and its tributaries.
  • Appendix C: Stream Buffer Width Literature Review (pdf) (2.41 MB)
    Scientific literature references related to effects of stream buffer width on water temperature.
  • Appendix D: Climate Change and Stream Temperature in Oregon - A Literature Synthesis (pdf) (997.58 KB)
    Inventory of the observed air temperature, stream temperature, and stream discharge trends in the Pacific Northwest documented in scientific literature.
  • Appendix E: Supporting Information for NPDES Permit Writers (pdf) (367.08 KB)
    Equations the Oregon Department of Environmental Quality permitting program typically uses to implement wasteload allocations consistent with a TMDL.
  • Appendix F: List of Restoration Projects (pdf) (197.48 KB)
    Summary of restoration actions that have occurred in the Umpqua Basin from the 2022 Oregon Statewide Status and Trends Report.
  • Appendix G: Water Quality Model Calibration and Scenario Reports (pdf) (49.72 MB)
    Configuration, calibration and scenario reports for the South Umpqua River, Umpqua River, and North Umpqua subbasin temperature models.
  • Appendix H: 2006 Appendix 2: Umpqua Basin Stream Temperature TMDL Supplemental Information (pdf) (11.69 MB)
    Analysis of Umpqua Basin stream temperature dynamics in both spatial and temporal scales.
  • Appendix I: 7Q10 Calculation Method (pdf) (133.81 KB)
    Specifies the 7Q10 calculation method used for assessment units in the Umpqua River basin.
• Response to Comments (pdf) (1023.51 KB, June 27, 2025)
  Summary of comments received during the public comment period for the draft TMDL and EPA's responses.

Public comments

EPA accepted public comments on its draft TMDL from October 9 through November 25, 2024. EPA's responses to the comments are provided above.

Contacts

For questions or additional information, please contact Rebecca Veiga Nascimento (veiganascimento.rebecca@epa.gov), 208-378-5767.