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Willamette Subbasins Temperature TMDL

Proposed rule

Rulemaking contact: Michele Martin, 503-880-7737

In 2013, the United States Environmental Protection Agency disapproved the Natural Conditions Criterion contained in Oregon's water quality standard for temperature due to the 2012 U.S. District Court decision for NWEA v. EPA, 855 F. Supp. 2d 1199 (D. Or., 2012). This portion of the temperature water quality standard was used in most temperature TMDLs issued from 2003 through 2012. On Oct. 4, 2019, the U.S. District Court issued a judgment for NWEA v. EPA, No. 3:12-cv-01751-HZ (D. Or., Oct. 4, 2019) and required DEQ and USEPA 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 water quality standard.

The temperature TMDLs for the Willamette Subbasins will be developed to address temperature listings for waterbodies upstream of the U.S. Army Corps of Engineers dams, as well as PGE's River Mill dam on the Clackamas River. DEQ will develop this TMDL by rule per Oregon Administrative Rule Chapter 340 Division 42.

This TMDL project includes the following Willamette Subbasins: Coast Fork Willamette, McKenzie, Middle Fork Willamette, Upper Willamette, Middle Willamette, Molalla-Pudding, North Santiam, South Santiam, Lower Willamette, and Clackamas Subbasins.

This project does not include waterbodies in the Tualatin Subbasin, Yamhill Subbasin, the Willamette River mainstem, and most of the major tributaries to the Willamette River. The temperature TMDLs for the Willamette River mainstem and major tributaries (exact extent summarized below) will be developed as a separate project with rule advisory meetings expected to begin in 2023 and scheduled for EPA approval or disapproval by Feb. 28, 2025.

Waterbodies in the Willamette mainstem and major tributaries project area include:

  • 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)
  • 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)
  • Blue River to Blue River Dam (approximately river mile 1.9)
  • 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)​


Public involvement

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EQC action

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