Final - Silver Bow Creek and Clark Fork River Metals TMDLs May 2014 Steve Bullock, Governor Tracy Stone-Manning, Director DEQ Document Number C01-TMDL-05aF Prepared by: Water Quality Planning Bureau Watershed Management Section Contributors: Water Quality Planning Bureau Watershed Management Section Eric Sivers, Metals Project Manager Jordan Tollefson, Metals Project Coordinator Dean Yashan, Section Supervisor Montana Department of Environmental Quality Water Quality Planning Bureau 1520 E. Sixth Avenue P.O. Box 200901 Helena, MT 59620-0901 Suggested citation: Montana DEQ. 2014. Final - Silver Bow Creek and Clark Fork River Metals TMDLs. Helena, MT: Montana Dept. of Environmental Quality. ACKNOWLEDGEMENTS The Montana Department of Environmental Quality (DEQ) would like to acknowledge multiple people and entities for their contributions to this document. Sections of this document were sent to stakeholders for review and input. The involvement of all reviewers led to improvements in this document and is greatly appreciated. DEQ would like to thank Sara Sparks and Peter Brumm of the U.S. Environmental Protection Agency; Joe Griffin, Brian Bartkowiak, and Bill Kirley of DEQ Remediation Division; Jeff May and Christine Weaver of DEQ Permitting and Compliance Division; Paul Lavigne, Gerry Paddock, and Terry Campbell of DEQ Technical and Financial Assistance Bureau; Will McDowell of the Clark Fork Coalition; and Molly Staats for their comments and contributions. Additionally, we would like to thank Pat Cunneen of the Natural Resources Damage Program, the Watershed Restoration Council, and the Town of Superior for their assistance with public outreach and meetings. Jonathan Drygas, a water quality assessor with DEQ, provided support for these Total Maximum Daily Loads (TMDLs) and was a vital member of the field crews that collected data for this project. Jordan Tollefson, a TMDL planner with DEQ’s Watershed Management Section, provided additional review and coordinated public outreach efforts. We would like to thank Janelle Egli, an administrative assistant with the Technical and Financial Assistance Bureau of DEQ, for her time and efforts formatting this document. Silver Bow Creek and Clark Fork River Metals TMDLs – Table of Contents TABLE OF CONTENTS Acronyms .................................................................................................................................................... vii Document Summary ..................................................................................................................................... 1 1.0 Introduction ......................................................................................................................................... 1-1 1.1 Background ...................................................................................................................................... 1-1 1.2 Water Quality Impairments and TMDLs Addressed by this Document ........................................... 1-2 1.3 Document Layout ............................................................................................................................. 1-5 2.0 Watershed Descriptions ....................................................................................................................... 2-1 2.1 Physical Characteristics .................................................................................................................... 2-1 2.1.1 Location ..................................................................................................................................... 2-1 2.1.2 Hydrology .................................................................................................................................. 2-1 2.1.3 Climate ...................................................................................................................................... 2-4 2.2 Ecological Profile .............................................................................................................................. 2-4 2.2.1 Land Cover and Land Use .......................................................................................................... 2-4 2.2.2 Aquatic Life ............................................................................................................................... 2-4 2.3 Cultural Profile ................................................................................................................................. 2-5 2.3.1 Population ................................................................................................................................. 2-5 2.3.2 Land Ownership ........................................................................................................................ 2-5 2.3.3 Transportation Networks .......................................................................................................... 2-5 2.3.4 Mining History ........................................................................................................................... 2-5 2.3.5 Remediation History ................................................................................................................. 2-6 3.0 Montana Water Quality Standards ...................................................................................................... 3-1 3.1 Silver Bow Creek and Clark Fork River Classifications and Designated Uses ................................... 3-1 3.2 Numeric and Narrative Water Quality Criteria ................................................................................ 3-3 4.0 Defining TMDLs and Their Components .............................................................................................. 4-1 4.1 Developing Water Quality Targets ................................................................................................... 4-2 4.2 Quantifying Pollutant Sources ......................................................................................................... 4-2 4.3 Establishing the Total Allowable Load ............................................................................................. 4-3 4.4 Determining Pollutant Allocations ................................................................................................... 4-3 4.5 Implementing TMDL Allocations ...................................................................................................... 4-5 5.0 Metals TMDL Components .................................................................................................................. 5-1 5.1 Effects of Metals on Designated Beneficial Uses ............................................................................. 5-1 5.2 Stream Segments of Concern .......................................................................................................... 5-1 5.3 Water Quality Data and Information Sources ................................................................................. 5-2 5/5/2014 Final i Silver Bow Creek and Clark Fork River Metals TMDLs – Table of Contents 5.4 Water Quality Targets and Comparison to Existing Conditions ....................................................... 5-2 5.4.1 Metals Evaluation Framework .................................................................................................. 5-2 5.4.2 Metals Water Quality Targets ................................................................................................... 5-3 5.4.3 Existing Conditions and Comparison with Water Quality Targets ............................................ 5-4 5.4.4 Metals Target Comparison and TMDL Development Summary ............................................. 5-26 5.5 Metals TMDLs ................................................................................................................................ 5-29 5.6 Metals Source Assessments ........................................................................................................... 5-35 5.6.1 Silver Bow Creek (MT76G003_020) Source Assessment ........................................................ 5-39 5.6.2 Clark Fork River: Warm Springs Creek to Cottonwood Creek (MT76G001_040) Source Assessment ...................................................................................................................................... 5-49 5.6.3 Clark Fork River, Cottonwood Creek to Little Blackfoot River (MT76G001_030) Source Assessment ...................................................................................................................................... 5-54 5.6.4 Clark Fork River, Little Blackfoot River to Flint Creek (MT76G001_010) Source Assessment ....... ......................................................................................................................................................... 5-55 5.6.5 Clark Fork River, Flint Creek to Blackfoot River (MT76E001_010) Source Assessment .......... 5-57 5.6.6 Clark Fork River, Blackfoot River to Rattlesnake Creek (MT76M001_030) Source Assessment ... ......................................................................................................................................................... 5-62 5.6.7 Clark Fork River, Rattlesnake Creek to Fish Creek (MT76M001_020) Source Assessment .... 5-63 5.6.8 Clark Fork River, Fish Creek to Flathead River (MT76M001_010) Source Assessment .......... 5-68 5.6.9 Source Assessment Summary ................................................................................................