LPLA advocates for sediment reduction and local restoration to protect Lake Pepin. Sediment reduction from upstream sources is the only sustainable strategy, but local restoration is necessary to maintain current uses, reverse ecological degradation, and redirect incoming sediment to have less overall impact.
For more information about this dual approach, see our blog posts:
The Sediment Reduction Strategy for the Minnesota River Basin and South Metro Mississippi River sets forth an interim goal of 25% sediment reduction in the Minnesota River by 2020. It also provides general water quality protection strategies for local watershed managers to consider in their ongoing planning efforts, recognizing that significant pollution reductions will require a combination of traditional conservation practices that reduce soil erosion from cropland and urban development areas, along with efforts to control near-channel erosion.The Sediment Reduction Strategy organizes Best Management Practices, or BMPs into several categories based on sediment and nutrient sources. Key BMP categories include:
Improve Riparian Buffers
Increase Water Storage
Limit Soil Erosion
Riparian zones, the ecosystems that occur along watercourses or water bodies, are critically important areas for protecting water quality throughout the Minnesota River Basin. Riparian zones that are planted in perennial vegetation act as protective “buffers” for the river and its tributaries. They trap and remove pollutants, such as sediment and nitrogen that are often contained in surface runoff waters, before those pollutants can enter the adjacent waterways. Perennially vegetative riparian areas also tend to be much less vulnerable to erosion because the root systems of vegetation act to hold soil in place. They also function to reduce water velocities, further lessening the likelihood that sediment and nutrient-rich organic materials will reenter waterways. Vegetative riparian areas also provide other important ecological benefits through creating habitat for highly valued wildlife; shading, and thus maintaining cool temperatures in waterways; and maintaining high-quality in-stream habitat for fish and invertebrates. Conversely, riparian areas planted in annual row crops have a greater potential for supplying excess nutrients and sediment to adjacent and downstream water bodies both because of their vulnerability to erosion and because they present no barrier to the overland flow of surface runoff. Riparian BMPs include: riparian herbaceous cover, riparian forest buffer, streambank and shoreline protection, and stream channel stabilization.
Water storage alleviates erosive forces acting on upland and near-channel sediment sources. It also encourages water filtration to reduce pollutants. Water storage BMPs include: sediment basins, ponds, water control structures, water and sediment control basins and maintenance, wetland restoration/creation, stormwater retention basins, public drainage management, push-up ponds, and pond maintenance.
Soil Loss Protection
Soil loss protection helps maintain the integrity of the soil and limit its movement from upland fields. Conservation Tillage is a key BMP that keeps the previous harvest residues on fields to stabilize soil and reduce surface flows. Government incentive programs are another BMP option that financially compensates landowners for protecting environmentally sensitive areas, often as an alternative to cultivation. Other soil erosion BMPs include: conservation cover, conservation crop rotation, residue and tillage management, contour farming, contour buffer strips, cover crop, critical area planting, no tillage, reduced tillage, ridge tillage, strip tillage, mulch tillage, windbreak establishment, windbreak management, filter strip, grade stabilization structure, grassed waterway, stormwater runoff control, and erosion control.
Nutrient management addresses the application and absorption of nutrients on agricultural fields. BMPs include: comprehensive nutrient management plan, nutrient management plan, waste water and feedlot runoff control.
Mitigating the problem at the source is crucial, especially for long-term sustainability, but waterways that are already experiencing impacts need ongoing management to ensure ecological health and human uses are protected. To learn more, check out the Lake Pepin Restoration Project.