Lake Superior Tall Clay Bluff Restoration Demonstration Project
Lake Superior Shoreline,
Minnesota Board of Water and Soil Resources
Basin Program Funds:
Thirty-six miles of the Minnesota Lake Superior shoreline are unstable tall clay bluffs. Nonpoint source pollution of Lake Superior is occurring all along the shoreline and throughout the watershed. Typically, the clay bank shorelines are quite high and the erosion and subsequent bluff instability have an extremely negative impact on the nearshore aquatic zone. There has been a need to develop guidelines and information on vegetative species which will grow well in conditions along Lake Superior shoreline areas.
It is estimated that the clay bluffs produce an estimated 70,000 tons of sediment annually, with 3,000 tons in Sucker Bay alone. One of the reasons why the final revegetation and bluff reshaping of the Sucker Bay project was not been completed earlier is that specific guidance on vegetative species which will grow well in these areas have not been compiled. The goal of this project was to provide a demonstration site and a visual example that all of the Lake Superior Association’s soil and water conservation districts, shoreline land owners, and other local governments could benefit from as a learning/information tool in their conservation efforts.
Final selection of the demonstration sites and preparation for plantings and bluff reshaping – including site survey, design layout and plant species selection – were completed. The project team developed construction documents, select a contractor, installed the plants, and reshaped the bluffs. Two properties were selected for restoration. A total of nine different treatments were applied to the nine different areas in order to compare many options side by side.
The different treatments included two types of vegetation, more than 700 hybrid poplars and dogwoods, tree shelters and mulch, major earthwork with erosion control blankets, hydraulically applied bonded fiber matrix, coconut wattle fascines, and fiber-reinforced earth. In addition to the savings at the two specific project sites, it is expected that many tons of sediment and pounds of phosphorus and nitrogen will be saved from future projects that will utilize the techniques learned from this project.
The project allowed the team to demonstrate several slope restoration techniques and revegetation schemes on tall clay bluff shorelines. The sites are being monitored and the lessons learned will provide valuable cost and erosion reduction benefits for the Minnesota Lake Superior shoreline property owners. The two sites will save an estimated 1,690 tons of sediment, 16,900 pounds of phosphorus and 3,380 pounds of nitrogen per year. The project team has been invited to present preliminary results at the 2002 Minnesota Water Planners Conference in September 2002.
Contact: Gene Clark, 218-723-4752