Final Revised Willamette Basin Mercury Total Maximum Daily Load Nov. 22, 2019 Watershed Management 700 NE Multnomah St. Suite 600 Portland, OR 97232 Phone: 503-229-5696 800-452-4011 Fax: 503-229-6762 Contact: Alex Liverman, Andrea Matzke, Kevin Brannan, Priscilla Woolverton www.oregon.gov/DEQ DEQ is a leader in restoring, maintaining and enhancing the quality of Oregon’s air, land and water. This report prepared by: Oregon Department of Environmental Quality 700 NE Multnomah Street Portland, OR 97232 1-800-452-4011 www.oregon.gov/deq Contact: Kevin Brannan Alex Liverman Andrea Matzke Priscilla Woolverton 503-229-6629 503-229-5080 503-229-5350 541-687-7347 Alternative formats: DEQ can provide documents in an alternate format or in a language other than English upon request. Call DEQ at 800-452-4011 or email [email protected]. Oregon Department of Environmental Quality ii Final Revised Willamette Basin Mercury TMDL and WQMP November 2019 Table of Contents Executive Summary ..................................................................................................................1 1. TMDL Introduction ..............................................................................................................3 1.1 TMDL Authority .................................................................................................................3 1.2 General TMDL approach...................................................................................................3 1.3 History of Willamette Basin Mercury TMDL ....................................................................... 6 1.4 Name and location ............................................................................................................7 1.4.1 HUCs, subbasins, and watersheds ....................................................................... 7 1.4.2 Land use ............................................................................................................... 9 1.4.3 Climate ................................................................................................................11 1.4.4 Stream Flow ........................................................................................................11 2. Beneficial uses .................................................................................................................. 12 3. Applicable water quality standards ................................................................................. 13 4. Mercury water quality impairments ................................................................................. 15 5. Summary of Mercury TMDL development and approach ............................................... 17 5.1 Mercury cycling in the environment ................................................................................. 17 5.2 Mercury TMDL approach ................................................................................................ 18 6. Explanation of models and current mercury load ........................................................... 20 6.1 Explanation of models ..................................................................................................... 20 6.1.1 Food Web Model .................................................................................................21 6.1.2 Mercury translator equation .................................................................................22 6.1.3 Linkage analysis using Mass Balance Model .......................................................25 6.1.4 Nonpoint source input data development .............................................................30 6.1.4.1 Atmospheric deposition ................................................................................. 30 6.1.4.2 Soil ............................................................................................................... 30 6.1.4.3 Groundwater ................................................................................................. 31 6.1.5 Estimation of instream delivery of mercury and reservoir processes ....................31 6.2 Current total mercury load estimation for the Willamette Basin ....................................... 32 7. Loading capacity and excess load ................................................................................... 34 7.1 Loading capacity ............................................................................................................. 34 7.2 Excess load .................................................................................................................... 34 8. Seasonal variation and critical condition ........................................................................ 39 9. Source assessment ........................................................................................................... 40 9.1 Air emissions .................................................................................................................. 40 State of Oregon Department of Environmental Quality iii Final Revised Willamette Basin Mercury TMDL and WQMP November 2019 9.1.1 Oregon permitted mercury air emissions ..............................................................40 9.1.2 National and global mercury emissions trends .....................................................40 9.2 Nonpoint sources ............................................................................................................ 41 9.2.1 Agriculture, forestry, non-MS4 permitted urban areas, and water conveyances ...41 9.2.2 Impoundments .....................................................................................................41 9.2.3 Legacy metals mining sources .............................................................................44 9.3 Background and unquantified anthropogenic sources ..................................................... 46 9.4 Point sources .................................................................................................................. 47 9.4.1 Wastewater permits and mercury loads ...............................................................47 9.4.1.1 Municipal sewage treatment plant permits .................................................... 47 9.4.1.2 Industrial wastewater permits ........................................................................ 49 9.4.2 Stormwater permits and mercury loads ................................................................51 9.4.2.1 Municipal stormwater permits ....................................................................... 52 9.4.2.2 Industrial Stormwater General Permits ......................................................... 54 9.4.2.3 Construction Stormwater Permits.................................................................. 54 10. Allocations .........................................................................................................................55 10.1 Load allocations for nonpoint sources ..................................................................... 58 10.2 Wasteload allocations for point sources .................................................................. 59 10.3 Instream surrogate targets ...................................................................................... 63 11. Margin of safety ................................................................................................................. 65 12. Reserve capacity ............................................................................................................... 66 13. Water Quality Management Plan ...................................................................................... 67 13.1 Introduction ............................................................................................................. 67 13.1.1 Implementation plans ...........................................................................................68 13.1.2 Adaptive management .........................................................................................69 13.2 Elements of the Water Quality Management Plan ................................................... 71 13.2.1 Condition assessment and problem description ...................................................71 13.2.2 Goals and objectives ............................................................................................72 13.2.3 Identification of designated management agencies and responsible persons ......72 13.3 Management strategies ........................................................................................... 73 13.3.1 Management strategies for nonpoint sources and water protection programs ......74 13.3.1.1 Oregon Department of Environmental Quality Nonpoint Source ................... 75 13.3.1.2 DEQ Cleanup Program—Abandoned Mine Lands Sites ............................... 76 13.3.1.3 DEQ Cleanup Program—Portland Harbor Superfund Source Control ........... 76 13.3.1.4 Oregon Department of Agriculture ................................................................ 77 13.3.1.5 Oregon Department of Forestry .................................................................... 81 13.3.1.6 Oregon Department of State Lands .............................................................. 84 State of Oregon Department of Environmental Quality iv Final Revised Willamette Basin Mercury TMDL and WQMP November 2019 13.3.1.7 Oregon Parks and Recreation Department ................................................... 87 13.3.1.8 Oregon Department of Geology