EQC202505ItemBAppG

DETP/25/1497

Item B: Willamette River Mainstem and Major Tributaries TMDL (Action) DEQ will present a revised Total Maximum Daily Load, or TMDL, to address temperature impairments in the Willamette River Mainstem and Major Tributaries. This rulemaking is part of a court order to update and replace multiple temperature TMDLs to make them consistent with current temperature standards. DEQ will request the commission adopt the Willamette River Mainstem and Major Tributaries TMDL as an amendment to the Willamette Subbasins TMDLs for temperature adopted by the commission in August 2024, by reference into rule. Attachments (Note: Attachment A is included in the staff report linked above.) Attachment B Total Maximum Daily Load Attachment C Water Quality Management Plan Attachment D Technical Support Document Attachment E TMDL and WQMP redline Attachment F Technical Support Document redline Attachment G Response to Comments TSD Appendices (Note: Only listing appendices being changed by this rulemaking.) Appendix A Heat Source Model Report Appendix D Assessment Units Appendix G Climate Change Summary Appendix H Interactive Map Appendix J Calibration Report Appendix K Model Scenario Report Appendix L McKenzie Model Scenario Report Appendix M Willamette River Mainstem and Major Tributaries Model Scenario Report Item B Presentation Slides