SEDIMENT REMOVAL FROM ACTIVE STREAM CHANNELS IN OREGON: Considerations for Federal Agencies for the Evaluation of Sediment Removal Actions from Oregon Streams. Developed with support from: US Fish and Wildlife Service National Marine Fisheries Service US Army Corps of Engineers US Environmental Protection Agency March 1, 2006 Version 1.0 Acknowledgements: This document has been developed through Federal interagency cooperation and dedicated staff, including: Janine Castro, FWS, Anne Mullan and Marc Liverman, NMFS, and John Barco and Shelly Hansen, USACE. Additional input was provided by the staff of the Oregon Departments of Fish and Wildlife, Environmental Quality, and State Lands, especially Christine Svetkovich, DEQ, Jim Brick and Patty Snow, ODFW, and Lori Warner-Dickinson, DSL. This document has incorporated to a great extent the National Marine Fisheries Service, Southwest Region Guidelines: “The Effects of Sediment Removal from Freshwater Salmonid Habitat” (Cluer, 2004), which can be viewed at: http://swr.nmfs.noaa.gov/hcd/policies/April19-2004.pdf. The NMFS Guidelines, authored by fluvial geomorphologist Dr. Brian Cluer, were extensively reviewed by independent recognized experts in the field of fluvial geomorphology, NMFS staff, aggregate industry representatives, independent consultants, and the Offices of General Counsel from the U.S. Department of Commerce and NMFS Southwest Region. Additionally, invited reviews from discipline experts were received from: Dr. Colin Thorne (Professor of Geography – University of Nottingham UK, and Colorado State University), Kris Vyverberg (Engineering Geologist - California Dept. Fish and Game – Sacramento, CA), Dr. Joan Florsheim (Geomorphologist - University of California – Davis, CA), and Dr. Thomas Dunne (Professor of Geomorphology – University of California - Santa Barbara, CA). An earlier White Paper, “Instream Aggregate Mining Issues in Oregon” (Castro and Cluer, 2003), was incorporated into this document as Chapter 3, Effect of Sediment Removal from Streams. The White Paper was reviewed by Federal and state agency personnel, industry representatives, and non-governmental organizations. Comments and suggestions from these reviews were incorporated to the extent possible in Chapter 3. 1 1 INTRODUCTION AND SCOPE ................................................................................5 1.1 Relevant Statutes............................................................................................................................ 6 1.2 Extent .............................................................................................................................................. 7 1.3 General Methods for Mining Aggregate ...................................................................................... 8 1.3.1 Instream Pit Extraction................................................................................................................ 8 1.3.2 Bar Scalping ................................................................................................................................9 2 STREAM FORM, FUNCTION, AND ANADROMOUS SALMONID HABITAT.......10 2.1 Stream Channel Dynamics .......................................................................................................... 10 2.1.1 Channel Form and Function ...................................................................................................... 12 2.2 Water Quality............................................................................................................................... 16 2.3 Floodplain / Channel Connection ............................................................................................... 16 2.3.1 Floodplains as Sources and Sinks.............................................................................................. 17 2.3.2 Riparian Communities............................................................................................................... 17 3 EFFECTS OF SEDIMENT REMOVAL FROM STREAMS .....................................19 3.1 Effects on Channel Morphology and Hydraulics ...................................................................... 20 3.1.1 Increased Width / Depth Ratio. ................................................................................................. 20 3.1.2 Bank Erosion............................................................................................................................. 21 3.1.3 Changes in Sediment Transport................................................................................................. 21 3.1.4 Reduced Sinuosity of the Mid-High Flow Channel................................................................... 22 3.1.5 Altered Sediment Sorting Processes.......................................................................................... 22 3.2 Alteration of the Sediment Transport Continuum.................................................................... 23 3.3 Effects on Habitat Components .................................................................................................. 25 3.3.1 Effects on Riffle Habitats. ......................................................................................................... 25 3.3.2 Effects on Pool Habitats. ........................................................................................................... 28 3.3.3 Effects on Riparian Vegetation ................................................................................................. 29 3.3.4 Effects on Stream Complexity and Diversity ............................................................................ 32 3.3.5 Effects on Water Quality........................................................................................................... 33 3.3.6 Fish and Wildlife....................................................................................................................... 34 3.4 Disturbance Regimes ................................................................................................................... 39 3.5 Summary of Effects...................................................................................................................... 40 4 CURRENT METHODS & RECOMMENDATIONS FOR SEDIMENT REMOVAL ..42 4.1 History........................................................................................................................................... 42 4.2 Introduction.................................................................................................................................. 44 2 4.3 Recommended Process to Evaluate Sediment Removal Proposals.......................................... 45 4.3.1 Identify appropriate sediment harvest locations........................................................................ 46 4.3.2 Identify species, life stages present, and habitat elements needed. ........................................... 49 4.3.3 Identify physical processes that create or maintain habitat elements. ....................................... 50 4.3.4 Select alternatives that minimize habitat disturbance and disruption of physical processes that create and maintain habitat. ..................................................................................................................... 51 4.4 Summary of Current Management Techniques in Oregon and their Limitations................. 52 4.4.1 Construction Best Management Practices ................................................................................. 52 4.4.2 In-Water Work Period............................................................................................................... 52 4.4.3 Turbidity.................................................................................................................................... 52 4.4.4 No Operation within the Active Flowing Stream or Below the Low Water Line ..................... 53 4.4.5 Grading and Shaping ................................................................................................................. 53 4.4.6 No Removal of Live Woody Vegetation................................................................................... 54 4.4.7 Leave Strips and Berms............................................................................................................. 54 4.5 Recommended Methods of Sediment Removal ......................................................................... 54 4.5.1 Design Discharge ...................................................................................................................... 55 4.5.2 Retaining Bar Form................................................................................................................... 56 4.5.3 Fish Passage .............................................................................................................................. 57 4.5.4 Restoration-Based Approach..................................................................................................... 58 4.5.5 Floodplain/Wetland Creation .................................................................................................... 58 5 MITIGATION ...........................................................................................................60 5.1 Mitigation Requirements............................................................................................................. 60 5.2 Mitigation Goals..........................................................................................................................