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Lower Columbia-Sandy Subbasin 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.

DEQ will present this TMDL to the Environmental Quality Commission for proposed rule adoption in November 2023. Per the District Court's final order and judgement, DEQ must amend and submit replaced temperature TMDLs to EPA for approval or disapproval. The schedule for the Lower Columbia-Sandy Subbasin TMDL will be submitted to EPA in November 2023, for determination by Jan. 15, 2024. 

Advisory committee

DEQ plans to hold two rulemaking advisory committee meetings for the Lower Columbia-Sandy Subbasin. The role of the rulemaking advisory committee is 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 Lower Columbia-Sandy Subbasin project area
  • Revisions to the Water Quality Management Plan
Committee documents
  • Advisory Committee Charter
  • Advisory Committee Roster


Public involvement

Webinar 2: March 21, 2023, 2 p.m. PT
DEQ held an informational webinar about the Temperature Total Maximum Daily Load Replacement for the Lower Columbia-Sandy Subbasin. The webinar provided an opportunity to exchange questions and answers about the technical approach to revising the TMDL.

Webinar 1: 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. The webinar provided information about the rulemakings and the technical approach to revising the TMDLs and the Water Quality Management Plans.  

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EQC action

Meeting has not yet been scheduled.