Temperature TMDL Replacement: Willamette Subbasins

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.

Project summary

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.

Rulemaking 

Willamette Subbasins TMDL and the amendment rulemakings