Water Quality Can Easily Erode Away
Soil erosion is one of the largest pollutants of lakes and streams in Minnesota (by volume), according to the Minnesota Lakes Association. Soils can reach a lake directly from the shoreline by water flowing into the lake through stream banks, cropland, ditches, or any other type of soil erosion within a lake’s watershed. The wind can contribute to sedimentation in a lake or river as well.
Although the impact of erosion within a watershed can vary greatly, the Minnesota Lakes Association reminds us that Agriculture is the main source of erosion in the State of Minnesota. Commercial and residential development adds to the erosion problem as do roads, driveway and roof tops.
The closer the source of erosion is to the lake or river the greater the sedimentation. Nearly 100 percent of the eroding soil is delivered into the lake from shoreline erosion. Much of the soil from eroding cropland is also washed into a stream or river during times of heavy rainfall. Once in the flowing water, soil particles fallout, or are deposited as sediment, before reaching the lake. However, varying degrees of soil particles stay suspended in the water, finally being deposited in the river or lake. This is especially true of silt and clay soils. This type of erosion and sedimentation can cause a practically irreversible, negative effect on fish habitat and aquatic plants.
Phosphorus, in excess, is a soil nutrient that in a lake causes major algae growth and oxygen depletion – resulting in lowering water quality in a major way. The Minnesota Lake Association assures us that 76 percent of Minnesota’s soils test high to very high for phosphorus. Therefore reducing soil erosion can significantly control pollution in a lake. Controlling erosion is everyone’s responsibility.
Shoreline owners can reduce erosion by planting vegetation along shorelines or on high bluffs to slow all runoff. Erosion can be reduced by leaving natural shoreline vegetation undisturbed, by minimizing paved areas that increase runoff and by stabilizing an eroding bank with riprap to prevent wave action from adding to erosion.
There are many new and proven methods of agriculture today that have reduced soil erosion as much as 90 percent. Fencing animals away from streams and running water preserves the quality of the water.
For assistance in shoreline erosion control projects always contact your local DNR for permit information. Many projects do not require permits. Call the Minnesota Lakes Association for additional information. 800-515-5253.