Lake Superior Shoreline Stabilization
Lake Superior, MN

Grantee: Minnesota Board of Water and Soil Resources
Basin Program Funds: $100,000
Non-federal Funds: $200,000
Project Duration: 08/1991 - 12/1994
Status: complete

Problem Statement
Approximately 60 miles of unstable clay embankment areas exist along the Minnesota shore of Lake Superior. The lake receives an influx of sediment as waves erode the unstable areas, and biological communities are concentrated in the nearshore zones due to the great depth of Lake Superior. Consequently, shoreline erosion has an extreme negative impact (physical and chemical) on the most biologically productive areas of the lake.

Background
The primary goal of the shoreline stabilization project is to minimize nonpoint source pollution to Lake Superior by preventing shoreline erosion. The project benefits both private and public landowners through incentives for stabilizing critical shoreline area (as defined by the Natural Resources Research Institute and the North Shore Management Board). Lake Superior has experienced a gradual rise in water levels since the early 1900's. Rates of shore erosion are greatest during periods of high water, and since mid-1985, Lake Superior's high water levels have caused extensive damage along Minnesota's North Shore. Although in many places the shore is composed of volcanic rock that resists erosion, much of the shoreland development is in erodible areas where the soils are predominantly clay and gravel. 37% of Lake Superior's sediment load is associated with clay bank erosion, with the most severe problems occurring in St. Louis County and Lake County, where wave action erodes the clay slopes. The program goal is to stabilize 2,000-3,000 feet of shoreline annually.

The Great Lakes Basin Program spent $190,000 over a four year period. Cost-sharing was made available through the Minnesota Board of Water and Soil Resources and local sources. In PY 1992, the Minnesota Board of Water and Soil Resources received its first Basin Program grant of $100,000 for two years. In PY 1993, the Soil Erosion and Sedimentation Task Force approved an additional $65,000 to continue the program. An award of $25,000 was added in PY 1994 to complete the Two Harbors Campground Project. For reporting purposes, the results and financial information from the PY 1992 grant ($100,000 over two years), the PY 1993 grant ($65,000 over two years), and the Two Harbors grant ($25,000) have been merged. Funding is used to implement erosion protection features, including site investigations (surveys and soil borings) and construction.

Activities
Shoreline erosion protection strategies (structural and nonstructural) are being implemented at several locations along the North Shore of Lake Superior. The Minnesota Board of Water and Soil Resources' lakeshore engineer has been working with local governments and landowners to implement the erosion protection features. In PY 1993, a total of 1,200 feet of shoreline stabilization was achieved on the LaBounty and Ion properties in Lake County, saving approximately 300 tons of soil per year. In PY 1994, the Ion project was extended another 100 feet to include the Erickson property, saving an additional 85 tons of soil per year.

Soil investigations and site surveys were completed at the Sewall site in PY 1993. In PY 1994, the lakeshore engineer completed preliminary project designs and cost estimates to protect approximately 100 feet of eroding shoreline. Final design was completed in PY 1995. An estimated 50 tons of sediment per year is expected to be saved by this project.

The Sucker Bay site is a quarter mile stretch of clay bank shoreline approximately 60 to 80 feet high. Sediment delivery to Lake Superior from this site is estimated at 5,300 cubic yards per year (6,050 tons per year) during high lake levels. In PY 1994, four property owners were involved in the project, which included the construction of a rock buttress along approximately 1,050 feet of highly eroding shoreline, saving an estimated 4,200 cubic yards (4,820 tons) of soil per year. The second phase of this project involved the design and construction of a surface and shallow groundwater collection system (to minimize water seepage and runoff to the face of the slope). Site surveys and preliminary designs for the second phase were completed in PY 1995, with construction scheduled for spring 1996.

In PY 1993, the Silver Cliff lakeshore site was stabilized using blast rock obtained from the nearby tunnel construction at Silver Cliff, along U.S. Highway 61. This project was completed as a demonstration, using nonconventional construction techniques and rock sizes, and is being monitored by the lakeshore engineer to provide information; this information may also be useful in other parts of the basin. Nearly 1,500 feet of shoreline was protected, preventing more than 1,017 tons of soil per year from entering the lake. In PY 1994, an additional 200 feet of shore protection was added (Austin property), saving another 170 tons of soil per year.

In PY 1994, site surveys, soil investigation, preliminary and final designs were completed for the Two Harbors Campground site. About 6,000 cubic yards of buttress rock and 2,700 cubic yards of armor stone were stockpiled at the project site. Additional armor stone was also used to protect a total of 1,425 feet of eroding shoreline. Construction of the project was completed in the winter of 1994-1995 (PY 1995). Approximately 1,320 cubic yards (1,515 tons) of soil will be saved per year by this project.

Also in PY 1995, final designs were completed for the Lamois and Loomis projects (over 600 feet of eroding Lake Superior shoreline), which will be completed in PY 1995. Estimated soil saved per year by these projects will be approximately 205 tons.

Results
The implementation of the Lake Superior Shoreline Stabilization project has saved approximately 2,414 tons of soil per year in PY 1993 and an additional 5,075 tons of soil in PY 1994. Completion of two additional projects (PY 1995), which were initiated by this grant (Two Harbors Campground; Sewall, Lamois, and Loomis properties) will save another 1,515 tons of soil per year. As a result of this entire project, the total soil savings is 8,986 tons per year. Over the last three years, Great Lakes Basin Program funds have leveraged approximately $190,000 from state sources and $190,000 from local contributions, totaling approximately $380,000. In addition, the lakeshore engineer is currently working on six new potential project sites along Lake Superior, resulting from the earlier successes of the Lake Superior Shoreline Stabilization project.

Contact: Gene R. Clark, (218) 723-4752

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