Your Lake, Our Lakes: Do we need to reforest our lakeshores?

Some lakeshore owners prefer the lawn-to-lake style, but there are drawbacks to this type of shoreland. Lawns to the lake decrease habitat and increase the runoff of nutrient-rich rainwater into the lake or river.

Water runs off lawns because grass roots are shallower than the roots of native vegetation and the soil under lawns often becomes compacted. The deeper roots of native vegetation enhance aeration and infiltration. Many lakeshore sites with lawns to the lake have been heavily graded during construction. The depressions and swales that would normally retard runoff are often graded over, topsoil removed, and the underlying soil compacted, making a flat lawn. But, flat lawns are more like pavement in their inability to infiltrate and retard stormwater runoff. Rainwater runoff from lawn-to-lake shorelines is 5 to 10 times higher than forested shorelines.

Runoff can be a major source of pollutants. Everything in the lawn, as well as on the streets and driveways, is carried by stormwater runoff into the lake. Water flowing over lawn surfaces picks up dirt, pesticides, toxic chemicals, fertilizers, pet waste, and other pollutants. Runoff often contains phosphorous, a plant nutrient, which can increase algae growth, and in turn lower water clarity. Just 0.2 pound of phosphorus can produce 100 pounds of algae. And although runoff from lawn-to-lake lakeshore sites varies considerably, on average a lawn-to-lake lot produces 0.2 pounds of phosphorous per summer compared to 0.03 pound per summer for a natural shoreland lot.

Minnesota soils are often phosphorus rich. So even an unfertilized lakeshore lawn allows seven to nine times more phosphorus to enter a lake than a naturally vegetated shoreline. Excess nitrogen, another plant nutrient, can also be transported to lakes from these lawns at higher rates.

Shoreline buffers can help minimize impacts associated with the lawn-to-lake style. These corridors of natural vegetation along rivers and lakes help protect water quality. A shoreline buffer of natural vegetation traps, filters, and impedes runoff. Buffers stabilize banks of lakes and rivers, offer scenic screening of shoreland development, reduce erosion, and control sedimentation. A natural shoreline also provides food and habitat for fish, waterfowl, songbirds, frogs, turtles, mammals, and butterflies.

In the past, many people thought that a lawn to the water’s edge was beautiful. But perceptions and laws are changing. Many people now realize that a manicured lawn impacts the ecological balance of the lake. Many agencies and organizations can help you learn more about shoreland buffers or the location of demonstration sites you can visit. Several links are available through the North Central Minnesota Lakes website at www.dnr.state.mn.us/lakes/ncml_j.html

The Governor's Clean Water Initiative pilot project brought people together to create an alternative set of shoreland development standards. Citizens that worked on the Shoreland Standards Update project recommended promoting naturally vegetated shorelines to protect lake water quality. The Alternative Standards could serve as the foundation for local government administered ordinances.

Details of the Shoreland Rules Update project are online at www.dnr.state.mn.us/waters

Click on the Governor’s Clean Water Initiative link). Email comments to shorelandupdate@dnr.state.mn.us

For more information, contact: Lakewaves@dnr.state.mn.us or DNR, Jean Goad 218-999-7911 or Erika Rivers 218-755-3645; U of M Extension, Eleanor Burkett, 218-828-2326; MPCA, Laurel Mezner, 218-828-6068