Ice pushup and erosion control
Greetings Sullivan Lake residents and property owners. This past winter was another year of inadequate snow cover so we saw more ice push up and erosion problems this spring. It is inevitable on some lakes, worse on some sides than others, and no one really knows how to prevent it entirely.
Following are some of our observations and experiences on your lake and others in the county.
Ice push up might happen once in ten years or every year to some degree. It generally happens when the lakes do not have adequate snow cover over the ice, and the spring thaw is erratic. Thawing and refreezing again and again, creates blocks of ice and the expansion pushes into the shoreline and is a very powerful source of energy. No amount of rock rip rap or vegetation can prevent this type of damage.
As I said, rock rip rap does not prevent push ups. It might help in lighter ice years, and if the rock is angular and irregular in shape and size, that lends to a bit more protection. However, most rock used for rip-rap in this area is field stone and round. The rip-rap itself might wind up pushed up along with the shoreline and now you have an even bigger mess to contend with.
Most shoreline owners don’t want to hear about aquatic vegetation but none-the-less, the aeration that aquatic vegetation provides to the lake, is the best preventative to ice problems. It might still occasionally happen, but not as likely, and not as severely.
The introduction of aquatic plants requires a permit from the DNR Division of Aquatics but you may also be able to get some established by allowing some existing vegetation to expand a bit. Thin in terms of having adequate clearing for boat traffic and perhaps a bit of swimming but if you can resist eliminating too much vegetation, it helps.
Our office does have State Cost Share dollars that can assist if a landowner desires to replant the shoreline to native materials and is willing to allow for a minimum of 20’ of buffer. Riparian buffers is still an erosion control practice that reduces shoreline erosion from wave action and natural causes. It also aids in runoff from lawn chemicals and grass clippings. If you are mowing lawn down to the waters’ edge, you add phosphorus to the water which creates algae growth and you are diminishing the quality of your lake water.
If shrubs and trees aren’t acceptable to you, try designating a “no-mow” zone of 12-15 feet. Allowing the grasses to reach their full height will not only filter nutrients from entering the lake, but the root growth will increase accordingly and hold the soil better.
Rock rip-rap is still an acceptable alternative, but is vastly overused in our county, and particularly on Sullivan Lake. You do need a permit from Morrison County Planning and Zoning for rock rip-rap and possibly from DNR if the rock extends into the water more than 7 feet. Some homes and cabins don’t have room to allow trucks and equipment to get close enough to install rock and it can be installed on the ice if necessary but there is usually some small adjustments needed by hand the following spring.
A very reasonable alternative, and much cheaper is the use of bio-logs. We have been using them for the past several years on the river and other lakes, and find them to be a much more natural and less expensive way to address the undercutting of a shoreline. Undercutting is when the base of your shoreline is cutting away at the waters edge, creating a shelf. The shelf sloughs off, and the process starts all over again. Riparian buffers and bio-logs do not require any permits.
Plants alone can be used sometimes to address undercutting, but in other cases, we will recommend the use of the logs. The logs are made of a coconut fiber and come in 10 foot sections. They come in various diameters. The logs are secured with wooden pegs hammered into the shoreline and lake bottom, or can be tied with cables. Vegetation can grow right through the log and we sometimes ask the landowner to shove willow cuttings right through the log into the soil. When developed, the logs aren’t even seen, and it allows the shoreline to look natural.
Our staff is available for technical assistance in helping you design a buffer area or addressing your erosion problems. And again, we may be able to offer financial assistance, on a case by case basis. Our phone number is 320-616-2479 and ask for Helen or Alan. We will either visit your shoreline on our own with your permission, or meet you there by appointment and discuss the various options to help you protect your valuable shoreline property.
Erosion Control Tidbits from MORRISON SOIL AND WATER CONSERVATION DISTRICT By Helen McLennan