Threats to our Lakes

Threats to
Our Lakes

Phosphorus

Phosphorus is a naturally occurring element that is found in leaves, soil, fertilizer, manure and many other common sources. Phosphorus is the limiting nutrient in most Minnesota lakes, meaning that when algae tries to reproduce, phosphorus is the required nutrient that runs out first.

For every one pound of phosphorus that finds its way into our lakes, 500 pounds of algae is able to form. When these algae blooms decompose, large amounts of dissolved oxygen are consumed which can cause large-scale fish die-offs.

Overdevelopment

DNR research shows that Minnesota has already lost 50% of its natural lakeshore and 1-2% more is being lost every decade. As small rustic cabins are converted to larger suburban style homes, shoreline vegetation, ice ridges, and trees are being removed in favor of impervious surfaces.

Forests and other vegetated lands serve as a giant natural sponge that filters and retain stormwater that helps to protect both surface and ground water. Studies have shown that once more that 25% of land in a lake shed is converted to other land uses, water quality begins to decline. Overdevelopment drastically increases the volume of runoff that reaches our lakes.

Runoff

When it rains, any water that isn’t absorbed into the ground, flows overland until it reaches surface water such as a lake or stream. Along the way, it picks up oil, debris, nutrients, loose dirt and anything else in its path, eventually dumping it into the water. Impervious surfaces like roads, roofs, concrete or anything else that water cannot flow through increases the amount of water and nutrients that are transported this way.

Chlorides

High amounts of chlorides are harmful to drink and are toxic to fish, aquatic bugs, plants and other wildlife. The primary source of chlorides in Minnesota is salt from winter de-icing. It takes just one teaspoon of salt to permanently pollute five gallons of freshwater, so it is critical that we apply just the right amount of salt to prevent excess waste.

You can help by not applying salt at temperatures below 15º since salt is ineffective at melting ice below this temperature. Upgrading old water softeners to newer models that use less or no salt can also help reduce chlorides that reach our lakes.

Phosphorus

Threats to
Our Lakes