An official website of the State of Oregon Learn How you know » (how to identify a Oregon.gov website) An official website of the State of Oregon »
You are here:
Project Area: 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.
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 were developed in two phases. The first phase addressed temperature listings for waters upstream of the U.S. Army Corps of Engineers dams, PGE's River Mill dam on the Clackamas River, and the McKenzie-Willamette River confluence. The second phase included the mainstem Willamette River and all the major tributaries downstream of the dams. The exact extents are described in the Quality Assurance Project Plans listed below. The TMDLs were phased to consider the extent of the water quality models being used to support the TMDLs, schedule requirements of the court order, and DEQ's available resources.
Final Willamette Subbasins TMDL documents, Amended May 2025
May 2025 TMDL Amendment documents
August 2024 TMDL documents
TMDL GIS data and interactive map
Quality Assurance Project Plans (QAPPs)
The Quality Assurance Project Plans listed below summarize the modeling and analysis methods used for the replacement temperature TMDLs in the Willamette Subbasins project area.
May 2025 rulemaking
Advisory Committee Documents
Meeting 3: July 30, 2024
Meeting 2: May 16, 2024
Meeting 1: March. 14, 2024
Public Involvement
Staff report: Willamette River Mainstem and Major Tributaries TMDL
August 2024 rulemaking
Meeting 2: April 6, 2023
Meeting 1: Feb. 23, 2023
Supporting documents
Sign up for email updates on TMDLs.
A .gov website belongs to an official government organization in the United States.
A lock icon ( ) or https:// means you’ve safely connected to the .gov website.
Your browser is out-of-date! It has known security flaws and may not display all features of this and other websites. Learn how
×