Agenda - Environmental Policy Board - 08/17/2015

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Shoreline Alterations: Riprap Installation of riprap is allowed only where there is a demonstrated need to stop existing erosion or to restore an eroded shoreline. An individual DNR Public Waters Work Permit is not required if the installation meets all of the following conditions: • The riprap must not cover emergent aquatic vegetation, unless authorized by an aquatic plant management permit from the DNR's Division of Fisheries. • Only natural rock (cannot average less than 6 inches or more than 30 inches in diameter) may be used that is free of debris that may cause pollution or siltation. Concrete is not allowed. • A filter of crushed rock, gravel, or filter fabric material must be placed underneath the rock. • The riprap must be no more than 6 feet waterward of the ordinary high-water level (OTIWL; see sidebar on page 1). • The riprap must conform to the natural alignment of shore and must not obstruct navigation or the flow of water. • The minimum finished slope waterward of the OHWL must be no steeper than 3 to 1 (horizontal to vertical). • The riprapped area must be no more than 200 linear feet of shoreline along lakes and wetlands or, along shorelines of streams, must be less than five times the average width of the affected watercourse. • The site must not be a posted fish spawning area, designated trout stream, or along the shore of Lake Superior. ordinary high water Ieuel average water Ieuel What are some other issues to consider? A row of boulders at the water's edge is not considered natural rock riprap. Rows of stacked boulders function as a retaining wall, and installation would require an individual permit from the DNR. Retaining walls are very damaging to the near -shore environment. Retaining walls cause wave action that scours the lakebed, displacing bottom sediment and creating an extremely sterile environment. The cumulative effect of numerous wall structures on a lake reduces critical habitat for fish and wildlife resources and much of the food chain they depend on. Retaining walls require structural maintenance and are frequently damaged by ice action and undermined by wave action. Riprap is not maintenance free and does not eliminate ice heaving, but it is easier to return the rocks to their original positions than to repair a wall. Consider planting within the riprap to add color, interest, and diversity. Live cuttings and plant plugs can be planted within riprap to provide additional slope stability and give your shoreline a more natural appearance. ©2003 State of Minnesota, Department of Natural Resources. Prepared by DNR Waters. Based on Minnesota Statutes 103C3 Public Waters Work Permit Program Rules Chapter 6115. DNR Contact Information DNR Information Center DNR Waters website lists Area Hydrologists: www.dnr.state.mn.us/ waters DNR Waters in St. Paul: 500 Lafayette Road, St. Paul, MN 55155- 4032, (651) 296-4800 DNR Ecological Services website provides informa- tion about aquatic plant management permits: www.dnr.state.mn.us/ecological services DNR Ecological Services in St. Paul: 500 Lafayette Road, Box 25, St. Paul, MN 55155, (651) 296-2835 Twin Cities: (651) 296-6157 Minnesota toll free: 1-888-646-6367 Telecommunication device for the deaf (TDD): (651) 296-5484 TDD toll free: 1-800-657-3929 This information is available in an alternative format on request. Equal opportunity to participate in and benefit from programs of the Minne- sota Department of Natural Resources is available regardless of race, color, national origin, sex, sexual orientation, marital status, status with regard to public assistance, age, or disability. Discrimination inquiries should be sent to Minnesota DNR, 500 Lafayette Road, St. Paul, MN 55155-4031; or the Equal Opportunity Office, Department of the Interior, Washington, DC 20240. Page 2 of 2