Erosion: Water Level Fluctuation

Description:

Water levels naturally change over the course of the season, but wide water level fluctuations or "bounce" can be dramatic on some lakes. Fluctuations in water levels can damage unstable and unvegetated shorelines. When planting near the water's edge, it is important to select native species that can tolerate "bounce" if you have significant water level fluctuations.

Bear Paw Resort near Park Rapids, Minnesota encompasses 650 feet of shoreline on Two Inlets Lake ("before" photo at top). In the spring of 2000, native grasses, wildflowers, shrubs, and aquatic plants were planted along 315 feet of their shoreline.

Two weeks after planting, several storms caused water levels to rapidly rise about 2 feet, and it took 3 to 4 weeks for water levels to return to their normal summer level. Many of the plants did not have enough time to get their roots down into the soil before the water levels rose, and either washed away or died (bottom photo). The high water levels also caused substantial erosion to the shoreline, requiring biologs to be installed in the fall before additional plants were added.

The deep-rooted native plants will hopefully become established and hold the soil in place should water levels surge again.