Defending Your Shoreline: Ice Damage

Filed in Maintenance, On The Lake by on March 3, 2014

ice damageFlooding, low water levels, invasive aquatic plants and shoreline erosion top the list of common concerns lake property owners expect to encounter each summer. During the winter months a less obvious problem can arise as a result of the annual ice cover and its subsequent recession.

Ice heaves occur in lakes of all sizes and are especially hazardous during winter where there is minimal insulating snow cover. This natural force forms mounds of earth called “ice ridges” that are deposited on shore. Occasionally, the force of these ice heaves is powerful enough to move trees and other structures on lake properties. More commonly, the ice damages docks, boat lifts and retaining walls and displaces sod, leaving a lumpy shoreline.

“The ice damage occurs worse in late winter. When we have a lot of snow, the ice is more insulated,” explains Julie Aadland, area hydrologist with the Minnesota Department of Natural Resources. “Any lake can be affected. It seems like a lot of the time it happens on lakes with sandy bottoms.”

As Aadland explains it, the ice covering the lake expands and then contracts. This movement causes cracks to form, which can fill with water. When this liquid freezes, it expands, pushing the ice sheet up against the shore.

“There’s really nothing you build that’s strong enough to push away the build-up of ice,” Aadland advises property owners looking to stave off the annual onslaught of ice.

The one solution some people have turned to is the challenging task of aerating the water. A pump can be used to keep water from freezing in front of a property. However, Aadland said few people take on this type or project because of the effort required. The pump must be constantly supervised and maintained, making it a viable option only if property owners live at their lake residence year-round.

Also, in order to aerate the water, property owners must work with the DNR to obtain the proper permit to use a water aeration device. This has to be carefully marked so people such as snowmobilers who might be driving over the frozen lake, are aware of areas of open water.

If property owners meet a set of specific criteria, they might not need a permit for removing or altering an ice ridge. According to the Minnesota DNR’s website, an individual Public Waters Work Permit would not be required from the DNR for ice ridge removal or grading under the following conditions:

  • The ice ridge resulted from ice action with the last year;
  • The project is either exempt from local permits or is authorized by issuance of a local government permit;
  • Not more than 200 feet of shoreline is affected;
  • All ice ridge material that is composed of sand or gravel is removed as provided above or graded to conform to the original cross-section and alignment of the lakebed, with a finished surface at or below the ordinary high water level;
  • No additional excavation or replacement fill materials occur on the site;
  • All exposed areas are immediately stabilized as needed to prevent erosion and sedimentation; and
  • Local zoing officials, the Watershed District, if applicable, and the Soil and Water District are given at least seven days prior notice.

Despite all of the drawbacks, there are a few benefits that accompany the annual ice invasion. Aadland said that when the ice push is not really severe, the encroaching ice sheet actually pushes up a helpful sand ridge onto the shore. This provided property owners with a nice deposit of sand for their beach area.

Ice ridges also help build up a natural protection for the lake. When rainwater lands on a lot and starts flowing toward the lake, these ridges prevent the storm water runoff from polluting the lake. The water gets caught against the ridge, where it is filtered through the soil before dispersing into the lake.

This year’s ample snow covering should naturally assist in minimizing the damage from ice heaves. However, as the ice melts away, high water levels should be taken into consideration.

If property owners have a structure close to the water, sandbagging might be necessary to prevent damage from flooding. To protect against rising water and wave erosion, a layer of riprap can be added to help retain soil, Pat Morstad, owner of Precision Landscape and Irrigation in Henning, says that while the majority of homeowners option for riprap, there are other man-made products that serve the same purpose. It all depends on the lay of the land and the look homeowners with to achieve.

“The worst erosion we have is where the lawn goes right to the shore,” Aadland says. “We promote planting natural vegetation on the shore. Your best protection against wave erosion is roots.”

She recommends property owners leave as many native plants as possible. For example, if a property owner wishes to protect a beach area, the best option would be to allow natural vegetation to grow on the rest of the shoreline. Keeping the property as close to its natural state as possible is the best way to prevent annual shoreline damage.

 

by Heidi Kratzke, a writer from Ottertail

 

 

Tags: , , , , , , ,