Adopted rule
Administrative Order No.: DEQ-12-2025
Filed and effective: May 9, 2025
See Oregon Bulletin, June 2025
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.
A Total Maximum Daily Load is a water quality restoration plan and the calculation of the maximum amount of a pollutant that a waterbody can receive while still meeting water quality standards for that particular pollutant. The maximum amount of loading a waterbody can receive is called the loading capacity. Loading from all pollutant sources must not exceed the loading capacity of a waterbody, including an appropriate margin of safety.
The Environmental Quality Commission adopted temperature TMDLs for the mainstem Willamette River and all the major tributaries downstream of the dams, except for the McKenzie River which is included in the Subbasins TMDL. For more information visit TMDLs for Willamette River Subbasins page.
DEQ plans to held three rulemaking advisory committee meetings for the Willamette River Mainstem and Major Tributaries Temperature TMDL. The role of the rulemaking advisory committee was to advise DEQ on the following:
- Economic and fiscal impacts of the proposed rules for entities impacted by the proposed TMDL
- Revision of required TMDL elements with a focus on the TMDL allocations to be updated based on the current temperature criteria for the Willamette River Mainstem and Major Tributaries project area
- Revisions to the Water Quality Management Plans
Meeting 3: July 30, 2024
Meeting 2: May 16, 2024
Meeting 1: March. 14, 2024