Exposed lake beds are subject to shoreland rulesWith abnormally low water levels exposing lakebed on many state lakes, the Minnesota Department of Natural Resources (DNR) reminds riparian property owners that what looks like "dry land" still may be subject to rules regulating what can and cannot be done on shoreland and in public waters.
With abnormally low water levels exposing lakebed on many state lakes, the Minnesota Department of Natural Resources (DNR) reminds riparian property owners that what looks like "dry land" still may be subject to rules regulating what can and cannot be done on shoreland and in public waters.
The DNR has been receiving numerous reports of people cutting, raking or otherwise disturbing aquatic plants in areas recently exposed by receding water levels. If these areas are below what's known as the ordinary high water level (OHW), any disturbance or removal of vegetation usually requires a DNR permit, and some activities are prohibited.
"Removal of emergent vegetation is a form of habitat destruction and it can have negative effects on fish, wildlife, and water quality," said DNR aquatic plant management specialist Sean Sisler. "It also could be illegal."
The OHW is an elevation indicating the highest water level that has been maintained for a sufficient period of time to leave evidence on the landscape; generally speaking, it's where natural vegetation changes from predominantly aquatic to predominantly terrestrial. For many lakes, the OHW is a set elevation that has been established by collecting data over several decades. The lakebed continues to be below the OHW even when it has been exposed due to low rainfall.
While fluctuating water levels can pose an inconvenience for riparian property owners, they're a natural and important part of lake ecology. Some emergent aquatic plants, such as bulrush, need periods of low water to germinate and re-establish depleted stands. Wildlife managers use periodic drawdown as a management tool to promote growth of emergent aquatic plants and improve waterfowl and wildlife habitat.
Emergent aquatic plants are protected by state law because they're extremely valuable to the health of lakes, fish, and wildlife. Such plants protect shorelines from erosion, stabilize bottom sediments, improve water quality by intercepting phosphorus before it reaches the water, provide valuable habitat for fish and wildlife, and protect nests from wave and wake action.
An aquatic plant management (APM) permit is required for control of emergent aquatic plants (bulrush, cattail, rushes, etc.) in public water basins, including aquatic plants that are growing on dry lake beds. Removal of emergent aquatic plants without a permit is a misdemeanor violation and can result in a fine and restoration order. Permit applications can be found online at http://www.dnr.state.mn.us/shorelandmgmt/apg/regulations.html.
Other activities undertaken below the OHW, such as grading or blading, filling with sand or gravel, and construction of boulder or other retaining walls, also are regulated and may require a DNR permit. Control of upland vegetation (e.g. tree saplings) growing in the exposed lakebed is not regulated by DNR. To minimize impacts to the lakebed of public waters, raking or dragging a device for control of upland vegetation should be limited to a width necessary for access to a dock. Remaining upland plants will die when higher water levels return.
The DNR also has received reports of people operating off-highway vehicles (OHV) on exposed lake beds. It is illegal to operate OHV on unfrozen public waters, or in a manner that causes wetland destruction.