Photo of a sandy lake shoreline adjacent to a forest. In the foreground several trees have fallen across the beach and into the lake. Their roots pull the bank down. The eroding bank is roughly three to four feet tall. Down the shore a point is littered with stones.At this location (photo above) on Douglas Lake, ice push and the power of wave action at high water levels can be devastating to near-shore banks and trees. The photo, taken from an adjoining property, shows our client’s property in the background. It includes the rocky area and a portion of the heavily eroded, bare bank. Note also the many uprooted and fallen trees, just a fraction of those lost over years of damage.

A close-up before picture shows stones and plastic weed barrier--from an improperly designed erosion control structure built roughly 20 years earlier--tumble down the steep shoreline into the lake.

The steep bank on our client’s site has been shaped by years of ice push events despite a previous effort to stop the erosion. Roughly 20 years ago, rip rap stones were installed over landscape cloth. This photo illustrates three problems with the previous installation:

  • First, using landscape cloth interfered with the establishment of plants that would otherwise grow between the stones and help stabilize the shoreline. Plant roots cannot readily penetrate the plastic material. The plants we use have deep, fibrous roots.
  • Second, the rocks were installed at too steep a slope, so instead of sliding up and onto them, ice pushed INTO the bank, destabilizing the entire structure.
  • Third, given the property’s orientation and the distance the wind travels across the open lake, the rocks used were too small for the expected waves. After the rocks were disturbed by the ice push, storm-driven waves washed many of them out into the lake, along with the newly exposed soils. The upper bank was then undercut, and the erosion worsened.

To address all three issues, our North By Nature team applied the current best practices in biotechnical and natural shoreline protection.

First, we removed as much of the old landscape cloth as possible. This will allow the owner to plant a selection of native shoreline plants into the rip rap where they will form a strong web of roots. These plants, along with the existing trees, will seed more native shoreline plants into the rip rap. Over time they will vegetate the upper bank.

CAD drawing showing the necessary gradual slope which will allow ice to ride up onto the stones instead of pushing them into the bank. Also shown are the stones sizes calculated to with stand wave action at the site given its orientation and fetch.

Second, the finished slope of the bank is engineered to be shallow enough to direct both expanding ice formations and windblown ice up and onto the protected shoreline instead of into the face of the bank.

Photo of work in progress: an excavator arm is used to roughly place the largest stones. Adric and Chris use hand tools to adjust them to achieve the required slope.

And finally, the stones were sized to remain in place even when three-foot waves batter the shoreline for days on end.

Almost an "after" photo: in the foreground the new stone rip rap slopes gently toward the lakeside, ready to deflect wave energy and ice for decades to come. Down the beach, the crew continues to install stone.

Visit the Shoreline Erosion Control gallery on our Photos page for before and after photos a few of our other shoreline projects.