* 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.  (2)

Ice - Ice expansion alone can exert 10-12 tons per square foot on anything in its way. If flooding occurs while the ice is still thick, strong winds can slam the ice ashore with a tremendous force. If the lake levels are above normal during freeze-up, sand and rocks captured in the ice can be lost to the lake during the spring. Every effort must be made to allow the ice to slide up and over the revetment instead of plowing into it. (1)

Rock revetments require some annual maintenance replacing rocks moved by the waves or ice. (1)