Ice is usually a cottager’s friend. We use it to keep our food cool on the drive to the cottage. It is needed to kick a refreshing glass of lemonade up a notch. It is a necessary ingredient for a batch of homemade ice cream. Yet sometimes ice can be the cause of your cottage nightmare.
Ice can cause massive shoreline and property damage. People have returned to their cottages in the spring, anticipating an exciting summer of cottaging ahead, only to find their second homes in shambles, the perpetrator melted away.
The Mechanisms of Ice
Kevin Gawne, a professional engineer with Manitoba Hydro and an expert on ice and shorelines, explains the mechanics of ice, “The mechanisms of ice inundation can be broken into shoving, pile-up, and ride-up however events typically consist of a combination of these mechanisms.” The contraction of ice is that it is relatively harmless; it’s the constant expansion and contraction of the ice that causes problems.
When temperatures drop, the cracks in the ice fill and freeze and when temperatures rise, the ice can’t move except at the edges. The expansion results in the ice thrusting onto banks. Each expansion and contraction cycle shoves the ice sheets further onto the bank making ice damage even worse when the winter is filled with numerous temperature fluctuations; the result is 8 tons of force per square foot pushing against the shoreline. The movement of the ice scrapes the shoreline, contributing to erosion problems.
Ice ridges (also called ice pushes or ice push ridges) are a normal occurrence in Canadian cottage country and are usually caused by ice heaving or ice jacking. Sand, sediment, and other bottom materials are pushed onto the shoreline when an ice sheet continues moving onto land. Ice ridges are a desirable thing as they prevent shoreline runoff, reducing the nutrient runoff to nearby water, and provide a shoreline habitat for plants, birds, and other animals. The ice ridges, which can be a metre or two in height during a normal Canadian winter, also help protect the area further up on the shoreline from being ruined by ice. If you mess with an ice ridge, ice may continue to work its way up your property and you may have a slab of ice for a coffee table.
Ice and Environmental Changes
Ice ridge environmental changes are often a cause of grief for cottagers. Once the ice has melted for the year, you may be left with a shoreline that looks like a bulldozer had a play date on your yard. But the natural berm caused by the ice ridges can make it difficult to use or block access the lake; in such cases it is impractical to leave the berm and action is taken. In such cases, the damage caused by ice ridges can usually be fixed with hand tools but check with your district first to see if you need a permit to make such repairs. Try to do your fixing without disturbing the natural vegetation.
If possible, consider leaving the shoreline alone. The mounds the ice ridge left behind offer a myriad of ecological benefits. The nutrients are a fertile breeding ground for plants and trees. The flora that takes over will create a root system that will soak up nutrients and help protect the shoreline from erosion. The shade from the shore plants provide a living space for organisms which support the fish in your area. In the long term, by leaving the berm alone, the following years as more ice pushing happens, more rocks get jammed into the area. The rocks, along with the deep-rooted plants and healthy soil, help to create natural shoreline protection. If you leave the natural berm untouched, you’ll have less long-term damage and the fish would send you a thank you note if they could!
Some cottagers feel that maintaining a natural shoreline helps – albeit minimally – to protect the banks against ice damage. Planting vegetation such as natural grasses and shrubs is ideal and has the added benefit of being a home for other plants and animals.
How Can You Minimize the Damage Done by Ice?
So what can you do? Ice’s power is so strong that erecting a retaining wall or making other shoreline changes in anticipation of damage is futile. Ice can push pile foundations out of line and cause docks and bridges to crumple like a child’s tower of building blocks. Cottages can be jostled off their foundations and massive rocks in rip rap are tossed aside like bowling pins. Engineering solutions are sometimes sought but they are usually ineffective and often expensive. Unfortunately there is little to be done to avoid ice’s wrath other than being forewarned that it can have the same effect as a bulldozer.
Kevin Gawne sums it up, “In general, four environmental forces can cause ice inundation: water currents (river or ocean), water level changes, rapid temperature changes, and wind.”
For more information, check out:
Payne, Amy L. Linwood Beach Residents Return to Find Ice Piled Around, Inside and Atop Their Homes.
Minnesota Department of Natural Resources, "Ice Damage to Shoreline Property."
Minnesota Department of Natural Resources, "Shoreline Alterations: Ice Ridges."
Rufer, Moriya. The Tremendous Power of Lake Ice.
Indiana Department of Environmental Management, "Ice Damage to Shoreline Properties."
(All the above were accessed October 22, 2010.)
Toby Welch - Toby is a full-time freelance writer who specializes in magazine articles, online writing, e-books, and manuscript editing.
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