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Temperature TMDL Replacement Project

DEQ has begun a project to revise multiple temperature TMDLs that were issued by DEQ and approved by EPA between 2004 and 2010. DEQ is under a court order to update and replace these temperature TMDLs to make them consistent with the current temperature standards. These TMDLs must be updated because they were based, in part on the Natural Conditions Criterion, a section of the temperature standard that was subject to litigation and has since been disapproved by EPA.

The following temperature TMDLs are being replaced:

Additionally, DEQ is updating the following TMDLs for temperature:

  • Upper Sucker Creek TMDL (1999)
  • Lower Sucker Creek TMDL (2002)
  • Lobster Creek Watershed TMDL (2002)
  • The Little River Watershed TMDL (2001)

Visit DEQ's TMDL page for more information on what TMDLs are and what they include.

​​In 2012, The U.S. District Court found that EPA’s approval of an element of Oregon’s water quality standard for temperature, the Natural Conditions Criteria, was unlawful. The Natural Conditions Criterion stated that where the natural thermal potential of all or a portion of a water body exceeds the biologically-based numeric temperature criteria in OAR 340-041-0028(4), the natural thermal potential temperatures supersede the biologically-based criteria, and are deemed to be the applicable temperature criteria for that water body. This portion of the temperature water quality standard was effective from 2003 until EPA disapproved it in response to the court decision in 2013. Information about temperature standard litigation is online. Many temperature TMDLs were based on this criteria, and this became the subject of a second lawsuit brought by the Northwest Environmental Advocates against EPA asserting the EPA unlawfully approved TMDLs that were based on the now disapproved Natural Conditions Criterion. The court issued a judgment on Oct. 4, 2019, requiring DEQ and EPA to replace 15 Oregon temperature TMDLs that were based on the Natural Conditions Criterion and to reissue the temperature TMDLs based on the remaining elements of the temperature criteria. Cumulatively, these TMDLs address over 700 temperature impaired segments that do not meet water quality standards for temperature. DEQ’s role is to develop and issue these TMDLs and submit to EPA for their action over an eight-year period.

Sept. 15, 2024*

  • Willamette Subbasins**: Coast Fork Willamette, McKenzie, Middle Fork Willamette, Upper Willamette, Middle Willamette, Molalla-Pudding, North Santiam, South Santiam, Lower Willamette, Clackamas Subbasins, McKenzie River to confluence with the South Fork McKenzie River (approximately river mile 56)​, South Fork McKenzie River to Cougar Dam (approximately river mile 4)​, and Blue River to Blue River Dam (approximately river mile 1.9)​​

  • Lower Columbia-Sandy Subbasin​​

*The court approved an extension for these TMDLs.​

**This TMDL will exclude the Willamette River mainstem and major tributaries. TMDLs for the Willamette River mainstem and major tributaries will be developed and issued for EPA’s approval or disapproval by Feb. 28, 2025.
Feb. 28, 2025

  • Willamette River mainstem and major tributaries
    Tributaries included in the Willamette mainstem and major tributaries project area:

    • Willamette River including all side channels and sloughs from the confluence of the Columbia River to the confluence of Coast Fork of the Willamette and Middle Fork of the Willamette Rivers (approximately river mile 187);

    • Multnomah Channel:

    • Clackamas River up to River Mill Dam/Estacada Lake (approximately river mile 26);

    • Santiam River (all 12 miles)

    • North Santiam River up to Detroit Dam (approximately river mile 49)

    • South Santiam River up to Foster Dam (approximately river mile 38)

    • Long Tom River to Fern Ridge Dam (approximately river mile 26)

    • Middle Fork Willamette to Dexter Dam (approximately river 17)

    • Fall Creek to Fall Creek Dam (approximately river mile 7)

    • Coast Fork Willamette to Cottage Grove Dam (approximately river mile 30)

    • Row River to Dorena Dam (approximately river mile 7.5)

  • Umpqua River Basin (North Umpqua, South Umpqua, and Umpqua Subbasins)

April 17, 2026

  • John Day River Basin

  • Rogue River Basin (Applegate, Illinois, Lower Rogue, Middle Rogue, and Upper Rogue Subbasins)

June 4, 2027

  • Snake River - Hell's Canyon

  • Lower Grande Ronde, Imnaha and Wallowa Subbasins

  • Middle Columbia-Hood, Miles Creeks

May 29, 2028

  • Walla Walla Subbasin

  • Willow Creek Subbasin 

  • Malheur River Subbasins

Additionally, DEQ is updating the following TMDLs for temperature:

  • Upper Sucker Creek TMDL (1999)

  • Lower Sucker Creek TMDL (2002)

  • Lobster Creek Watershed TMDL (2002)

  • The Little River Watershed TMDL (2001)

​Note: The data solicitation closed on Oct. 30, 2020.

To support the replacement of these temperature TMDLs, DEQ will be conducting an open data solicitation starting July 1, 2020, through the end of the day, Oct. 30, 2020. During the solicitation period, the public may submit temperature data to DEQ in the watersheds subject to the temperature TMDL replacements.

For questions about the data solicitation, email:

What is the data going to be used for?

The primary use of the data is to characterize stream temperatures in watersheds where DEQ must revise the temperature TMDLs. Specifically, the data may be used to characterize temperature patterns and variation over both spatial and temporal scales and determine where exceedances to the temperature water quality standards occur and the magnitude and duration of those exceedances. Depending on the location and time period the data were collected, the data may be used to support the temperature modeling analysis. The modeling analysis helps DEQ understand the sources of temperature warming and what actions will reduce that warming. DEQ will highlight the years and waterbodies where temperature data will be extremely useful. In most cases, DEQ will make data submitted publically available in our Ambient Water Quality Monitoring System database.

Data quality and submission guidelines 




Data availability​ and priorities

​​TMDL development and implementation is a public process. That means DEQ will work to keep the public informed and will consider their concerns and ideas. Each project TMDL will include a rule advisory committee to provide information and feedback on the TMDL during development, as well as a web page for each TMDL with meeting materials and project updates. DEQ will incorporate environmental justice practices to make participation as open and accessible as possible. Additionally, DEQ will have a formal public comment period where anyone can provide comments. DEQ will develop a response to comment document that will be available to the public. For rulemaking information, visit the rulemaking webpages.

DEQ will provide two informational webinars about the Temperature Total Maximum Daily Load Replacements. The webinars will provide an opportunity to exchange questions and answers about the technical approach to revising the Lower Columbia-Sandy Subbasin and Willamette Subbasins TMDLs.

Lower Columbia-Sandy Subbasin on March 21, 2023, at 2 p.m. PT. 

Willamette Subbasins on March 22, 2023, at 1 p.m. PT. 

Webinar - Jan. 31, 2023

DEQ held an informational webinar about the Temperature Total Maximum Daily Load Replacements for the Lower Columbia-Sandy Subbasin and the Willamette Subbasins on Jan. 31, 2023. The webinar provided information about the rulemakings and the technical approach to revising the TMDLs and the Water Quality Management Plans.


For more information on the Temperature TMDL Replacement Project please contact:

Email the program about questions about the data solicitation.

Sign up for email updates on TMDLs

TempReplacementMap20202.pngClick for map of affected areas
Updated September 2022