Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 1 Understanding, Living With, & Controlling Shoreline Erosion A Guidebook for Shoreline Property Owners Third Edition Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 2 Acknowledgments The Tip of the Mitt Watershed Council is the voice for Northern Michigan’s waters. We are dedicated to protecting our lakes, streams, wetlands, and ground water through respected advocacy, innovative education, technically sound water quality monitoring, and thorough research. We achieve our mission by empowering others and we believe in the capacity to make a difference. We work locally, regionally, and throughout the Great Lakes Basin.We were formed in 1979 and have a history of working closely with lake associations and shoreline property owners on water resource management issues. The first printing of this guidebook was made possible by a grant from the U.S. Environmental Protection Agency through the Great Lakes Commission’s Great Lakes Basin Program for Soil Erosion and Sedimentation Control. Doug Fuller authored the first edition. Third Edition printing made possible with funding provided by the Jimmy F. New Foundation. www.jfnfoundation.org Copyright © 2007 by Tip of the Mitt Watershed Council 426 Bay Street, Petoskey, MI 49770 phone: 231.347.1181 fax: 231.347.5928 e-mail: [email protected] website: www.watershedcouncil.org ISBN 978-1-889313-11-4 Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 3 Table of Contents Section One: Introduction to Shoreline Erosion……………………………………………...1 Section Two: Understanding Shorelines and Shoreline Erosion……………………………..4 Shoreline Types……………………………………………………………………………………………5 Streams and Streambanks…………………………………………………………………………………7 Lakeshores………………………………………………………………………………………………..12 Section Three: Impacts of Shoreline Erosion………………………………………………..18 Section Four: Assessing Lakeshore and Streambank Erosion……………………………….21 Identifying the Causes……………………………………………………………………………………22 Site-Specific Causes……………………………………………………………………………………...23 Systemic Causes………………………………………………………………………………………….25 Section Five: Methods of Preventing Shoreline Erosion on Inland Lakes and Streams……………………27 Access Control and Protection………………………………………………………………………….28 Rock Preservation…………………………………………………………………………………………28 Ice-Shove Ridge Protection……………………………………………………………………………...28 Building Setback…………………………………………………………………………………………28 Careful Watercraft Operation……………………………………………………………………………29 Shoreline Vegetation Preservation and Management…………………………………………………...29 Wetland Protection……………………………………………………………………………………...30 Control Overland Runoff, Erosion, and Sedimentation………………………………………………...30 Progressive Watershed Management…………………………………………………………………….30 Section Six: Methods of Controlling Shoreline Erosion on Inland Lakes and Streams………………...31 Biotechnical Erosion Control……………………………………………………………………………32 Rock Revetments………………………………………………………………………………………...38 Bulkheads………………………………………………………………………………………………...46 Groins…………………………………………………………………………………………………….48 Beach Fills………………………………………………………………………………………………..49 Infiltration and Drainage Controls………………………………………………………………………50 Slope Flattening………………………………………………………………………………………….50 Breakwaters……………………………………………………………………………………………….51 No Action………………………………………………………………………………………………..52 Section Seven: Eight Basic Steps to Planning and Implementing…………………………..54 Section Eight: Case Study…………………………………………………………………….58 Section Nine: Appendices…………………………………………………………………….65 One: Inland Lakes and Stream Erosion Reference Guide……………………………………………...66 Two: Examples of Shoreline Erosion Evaluation Worksheets and Severity Indexes…………………...73 Three: Critical Planting Guidelines.…………………………………………………………………….78 Four: Shoreline Erosion Control Plants………………………………………………………………...83 Five: Commercial Sources of Plants…………………………………………………………………….93 Six: Sources of Shoreline Erosion Products……………………………………………………………..96 Seven: Regulatory Agencies and Potential Sources of Technical Assistance in Michigan…………….98 Eight: Glossary…………………………………………………………………………………………107 Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 4 Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 5 Section One Introduction to Shoreline Erosion Waves gradually expend their energy on this sloping gravel shoreline helping to protect shoreline soils against erosion. Shorelines do not exist in an unchanging condition… Unfortunately, nature's dynamic equilibrium and human efforts to control it are often a poor mix. Understanding, Living With, and Controlling Shoreline Erosion Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 6 Section One: Introduction to Shoreline Erosion Erosion is the wearing away of the land surface by the Large scale efforts to control accelerated soil erosion action of wind, water, ice, or gravity. Sedimentation and sedimentation, from both inland and shoreline is the deposition of eroded soils in waterways or sources, have been ongoing by a variety of state and other locations. federal agencies since the dust bowl conditions of the 1930’s. In the past, much of the focus of shoreline Shorelines do not exist in an unchanging condition. erosion and its control has been on the coastlines of Erosion and the transport and deposition of sediments the oceans and the Great Lakes, where erosion has are natural processes along shorelines. There is often the potential to be most severe and have catastrophic a net balance between the amount of shoreline eroded consequences. The approach has often been one of and the amount of new shore- pure structural engineering, line created by sedimentation without considering the – a condition known as influence of, or impact to, dynamic equilibrium. ecological systems. Natural erosional processes Information pertaining typically proceed very slowly, specifically to inland lakes on a geologic rather than a and streams has been slow human time scale. The plants to develop, has been largely and animals that live along unavailable to shoreline the shoreline can adjust to property owners in an these slow changes, main- understandable form, and taining a stable, healthy, has generally not taken an productive ecosystem. In ecosystem approach. As a fact, some species have result, some accelerated adapted to live in erosional erosion problems have gone areas. For example, bank unnoticed or unchecked, swallows nest in steep, and many erosion control eroding bluffs and wood projects which have been turtles lay their eggs in constructed are either eroding sandy streambanks. inappropriate or ineffective Studies have revealed that for inland waters. preventing natural shoreline processes can upset overall The trend in recent decades ecosystem stability. Trying for shoreline living, coupled to eliminate all shoreline with shoreline development change is like trying to still patterns, has contributed the very waves and currents to accelerated erosion. that cause it. Emergent marsh plants, such as this hardstem bulrush Natural shoreline erosion (Scirpus acutus), have disappeared in many areas following is also now perceived as Human activities or distur- shoreline development, exposing the shore to greater a problem, whereas on erosive forces. bance along shorelines and previously undeveloped throughout watersheds can shorelines subtle changes bring about changes that greatly accelerate the in shoreline configuration were rarely noticed and natural erosional process, often with profound not considered a situation that needed controlling. environmental or economic impacts. Accelerated Some lakeshore developments do away with the erosion can lower the stability and productivity of natural shoreline in favor of bulkheads or other aquatic habitats and may have serious implications erosion control structures as a matter of course. for landowners. Quite often these structures are not needed. 2 Shoreline_Book2006FINAL:Shoreline_Book2006 2/6/07 8:25 AM Page 7 Section One: Introduction to Shoreline Erosion Many people in our society do not accept the New methods and refinements of old methods are moveable nature of shoreline property, but rather constantly being developed. Each site involves a seem to expect that shorelines will be permanently unique set of circumstances and generally requires fixed in perpetuity and recorded as such in land a customized solution. titles, similar to other surveyed property boundaries. Unfortunately, nature’s dynamic equilibrium and Even though there have been numerous studies human expectations as well as our efforts to control and publications on this topic, there are no manuals it are often a poor mix. with generic plans for shoreline protection projects which are guaranteed to work. However, by utilizing This guidebook focuses on the erosion and sedimen- the information contained in this guidebook and tation caused by the energy of streams and inland following an organized plan to assess problems and lakes acting on their shorelines. Its goal is not to evaluate the pros and cons of potential solutions, the help shoreline property owners make their shoreline likelihood of choosing an appropriate and successful unchanging, but rather to inform about shoreline action will be improved. processes and help guide actions to control nature in a way that is not utterly futile or environmentally harmful. It attempts to present an unbiased overview of the pros and cons of different methods. However, it seems clear to Watershed Council staff that one method, biotechnical erosion control,