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National Management Measures to Control Nonpoint Source Pollution from Hydromodification

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National Management Measures to Control Nonpoint Source Pollution from Hydromodification United States Environmental Protection Agency Office of Water Washington, DC 20460 (4503T) EPA 841-B-07-002 July 2007 National Management Measures to Control Nonpoint Source Pollution from Hydromodification Nonpoint Source Control Branch Office of Wetlands, Oceans and Watersheds U.S. Environmental Protection Agency Office of Water July 2007 Disclaimer This document provides technical guidance to states, territories, authorized tribes, and the public for managing hydromodification and reducing associated nonpoint source pollution of surface and ground water. At times, this document refers to statutory and regulatory provisions, which contain legally binding requirements. This document does not substitute for those provisions or regulations, nor is it a regulation itself. Thus, it does not impose legally-binding requirements on EPA, states, territories, authorized tribes, or the public and may not apply to a particular situation based upon the circumstances. EPA, state, territory, and authorized tribe decision makers retain the discretion to adopt approaches to manage hydromodification and reduce associated NPS pollution of surface and ground water on a case-by-case basis that differ from this guidance where appropriate. EPA may change this guidance in the future. Table of Contents Table of Contents Chapter 1: Introduction................................................................................................................ 1-1 What is Hydromodification?............................................................................................... 1-1 Why is NPS Guidance on Hydromodification Important? ................................................. 1-2 Purpose and Scope of the Guidance.................................................................................... 1-4 Document Organization...................................................................................................... 1-4 Activities to Control NPS Pollution.................................................................................... 1-5 Historical Perspective ................................................................................................1-5 Federal Programs and Funding ..................................................................................1-5 Introduction to Management Measures .............................................................................. 1-7 Channelization and Channel Modification (Chapter 3).............................................1-8 Dams (Chapter 4).......................................................................................................1-9 Streambank and Shoreline Erosion (Chapter 5).........................................................1-9 Chapter 2: Background ................................................................................................................2-1 Key Geomorphic Functions of Streams..............................................................................2-1 Discharge, Slope, and Sinuosity ................................................................................2-1 Erosion, Transport, and Deposition of Sediment.......................................................2-2 Dynamic Equilibrium.................................................................................................2-2 Longitudinal View of Channels.................................................................................2-4 Disruption of Dynamic Equilibrium ..........................................................................2-6 General Impacts of Channelization and Channel Modifications ........................................2-6 Physical Impacts ........................................................................................................2-6 Chemical Impacts.......................................................................................................2-7 Biological and Habitat Impacts..................................................................................2-8 Impacts Associated with Specific Hydromodification Actions........................................2-10 Channel Straightening and Deepening.....................................................................2-10 Channel Lining.........................................................................................................2-10 Channel Narrowing..................................................................................................2-11 Channel Widening ...................................................................................................2-11 Culverts and Bridges................................................................................................2-11 Urbanization.............................................................................................................2-12 Agricultural Drainage ..............................................................................................2-13 Shorelines..........................................................................................................................2-14 Shoreline Processes..................................................................................................2-14 Deposition and Erosion............................................................................................2-15 Common Natural and Anthropogenic Causes of Coastal Land Loss ......................2-16 Impacts Associated with Dams.........................................................................................2-16 Water Quality in the Impoundment/Reservoir.........................................................2-18 Water Quality Downstream of a Dam .....................................................................2-21 Suspended Sediment and Reduced Discharge .........................................................2-21 Biological and Habitat Impacts................................................................................2-22 Impacts Associated with Dam Removal...........................................................................2-23 Physical Changes: Upstream Impacts......................................................................2-24 Physical Changes: Downstream Impacts.................................................................2-24 EPA 841-B-07-002 i July 2007 Table of Contents Biological Changes: Upstream Impacts...................................................................2-25 Biological Changes: Downstream Impacts..............................................................2-26 Chapter 3: Channelization and Channel Modification.................................................................3-1 Management Measure 1: Physical and Chemical Characteristics of Channelized or Modified Surface Waters .................................................................................................... 3-2 Management Practices for Management Measure 1..................................................3-3 Planning and Evaluation ...................................................................................3-3 Operation and Maintenance Programs..............................................................3-4 Grade Control Structures ............................................................................3-4 Levees, Setback Levees, and Floodwalls....................................................3-5 Noneroding Roadways................................................................................3-5 Streambank Protection and Instream Sediment Load Controls ..................3-6 Vegetative Cover ........................................................................................3-7 Summary of Physical and Chemical Practices............................................3-8 Management Measure 2: Instream and Riparian Habitat Restoration.............................. 3-10 Management Practices for Management Measure 2................................................3-10 Planning and Evaluation .................................................................................3-11 Biological Methods/Models......................................................................3-11 Temperature Restoration Practices ...........................................................3-12 Geomorphic Assessment Techniques .......................................................3-13 Expert Judgment and Checklists...............................................................3-16 Operation and Maintenance Activities............................................................3-16 Chapter 4: Dams ..........................................................................................................................4-1 Management Measure 3: Erosion and Sediment Control for the Construction of New Dams and Maintenance of Existing Dams.......................................................................... 4-4 Management Practices for Management Measure 3..................................................4-5 Erosion Control Practices .................................................................................4-5 Runoff Control..................................................................................................4-7 Erosion and Sediment Control (ESC) Plans .....................................................4-8 Management Measure 4: Chemical and Pollutant Control at Dams................................. 4-10 Management Practices for Management Measure 4................................................4-11 Management Measure 5: Protection of
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