WINTER CHANGES TO SHORELINE EXPLAINED
Submitted by John Chambers
Winter can result in substantial changes to the shoreline of the lakes in our watershed. Ice can push mud, clay, soil, and rock from the bottom of the lake and from along the shoreline up onto the land, often resulting in large ridges or mounds. The mounds or ridges are referred to as “ice ridges”, “ice pushes”, or “ramparts”.
But how do these ice ridges occur and what causes them?
Ice on the lake expands naturally when temperatures increase, pushing outwards.
Cracks form in the ice when there are different temperatures at the top and bottom of the ice and different expansion rates. This occurs more often when there is not a lot of snow cover to provide insulation and the top of the ice warms up more quickly. When water rises into these cracks and freezes, it causes the ice to expand and push out.
Warming and cooling of the ice sheets with changing temperatures pushes the ice towards the shore and can scrape and push material from the lake bed and shoreline into mounds (Minnesota Department of Natural Resources, 2012).
If ice ridges have occurred on your property, this means your shoreline is prone to ice heaving and you will probably continue to get more ice ridges over time.
What actions can homeowners take when ice ridges impact their property?
“There are a few options homeowners have that they can consider when they have been impacted by ice ridges,” said Stacy Porter, Planning and Regulation Technician with Kawartha Conservation. “Homeowners can choose to do nothing, which ultimately creates a barrier on their property, or they can consider restoring their property to its original grade, among other things.
“It is important, whichever option homeowners take, that they are familiar with the steps to take and the permissions that may be required from the conservation authority,” Ms. Porter added.
Ice ridges protect shorelines from ice and wave damage. They often create a barrier that prevents sediment and other nutrients from entering into the lake and at the same time they create fertile soil where plants can grow. The roots of the plants help to further stabilize the shoreline and take up nutrients as well as provide shade and habitat for birds, fish and other wildlife.
As ice heaving is a natural process, homeowners who choose to re-grade their property may need to do so again in the future.
To learn more about ice jacking and how to address issues with your property review the Ice Ridges Fact Sheet at http://kawarthaconservation.com/permits-planning/permits.