Section 10: Best Management Practices for Achieving High Water Quality
High water quality is a valuable resource. The quality of water used for drinking, cooking, and agriculture directly affects public health, safety, and welfare. Water quality is also important for fish and wildlife habitat, recreation, transportation, and industry. The natural water system stores and cleanses water but there are limits to its effectiveness.
Water is available in surface waters, groundwater, and rain and other precipitation. It is vital to control the substances added to any of these systems in order to preserve the highest water quality.
- Water Pollution is the introduction of any foreign material into water, or other impact on water, which produces undesirable changes in the physical, biological, or chemical characteristics of the water. Air pollution needs to be controlled because it can contaminate our water through rainfall. Both groundwater and surface waters are affected by our land use practices. Vegetation and soil are natural filters of water and can actually break down some chemicals and toxins to make them less harmful.
In addition to toxic pollutants, excessive nutrients like nitrates and phosphates can degrade water quality. They are the primary cause of excessive algae and bacteria in lakes. Nutrients are introduced into the system by excessive or improper application of fertilizers in agricultural, lawn, and garden uses; faulty sewage treatment systems; and concentrated storm water runoff. There are two types of pollution sources:
- Point source pollution comes from a specific point like a pipe.
- Nonpoint source pollution results from improper land management, overfertilization, erosion, and sedimentation. The amount from one source may be small, but cumulative amounts can cause severe water quality problems.
Best management practices
"What can I do to improve water quality and shorelands?" The way land is managed has a large impact on the quality of water and ecology of lakes, rivers, and shorelands. The DNR has adopted management guidelines called Best Management Practices (BMPs) that help maintain and improve quality shoreland environments.
The following are basic principles that property owners can observe to help improve water quality and shorelands. More details are available in the Best Management Practices Guides that have been prepared for agriculture, forestry management, and urban areas.
- Filter Strips - These are areas adjacent to the shores of water bodies that help prevent contaminants from entering the water. The best filter strip is mature woodland with full ground-level, mid-story, and upper-story growth. The filter's effectiveness drops off as the amount of vegetation decreases. Full-height native prairie grasses along the shore are more effective as filters than short mowed lawns. The width of the filter strip also affects its filtering capability. For agricultural lands, a minimum width of 50 feet is required. Maintain or plant native vegetation over as much of the property as possible to provide the best filtration.
- Sewage Treatment - Maintaining a proper sewage system will prevent contaminants from leaking into the groundwater and surface waters.
- Erosion and Sediment - Soil erosion and sediment contain nutrients that promote excessive algae and bacteria in lakes. Stabilize and correct erosion problems as they occur by using mulch, sod, and other methods to minimize soil exposure and loss.
- Lawns and Gardens - Carefully evaluate the need for lawn area. Watering can waste valuable groundwater. Lawns are poor at filtering out contaminants in runoff water before it enters the lake. Lawn fertilizers, pesticides, and herbicides have a tendency to reach the water systems and degrade them. Plant gardens away from the water's edge, use only safe additives, and control erosion.
- Toxic Chemicals- Avoid using toxic chemicals as much as possible. Use biodegradable soaps and household products, and carefully handle gasoline and motor oils, especially when on or near water. Properly dispose of used oil, paint products, and other toxins.
- Storm Water Runoff - Natural storm water runoff can usually be handled by the natural landscape. Increased runoff can be caused by buildings, roads, driveways, and patios. These changes add "hard" surfaces that are impermeable to water. Concentrations of storm water can cause flooding, erosion, and loss of valuable water, which otherwise would infiltrate and recharge groundwater systems. Building sizes and hard surfaces should be minimized to help reduce the amount of runoff.
- Species and Habitat Diversity - Diversity applies to both the plant and animal communities. Diversity makes plant communities more interesting and stimulating to humans, as well as more ecologically sound. Diverse and balanced species populations are healthier because they are more resistant to disease and other changes in the environment. Shoreland areas provide a unique ecological zone that is required for certain plant and animal species. Destroying this to replace it with lawn and unnecessary structures robs the community of this diversity. Once this type of landscape is destroyed, it is difficult to replace. Maintain as much of the natural landscape as possible to promote a diverse, interesting, and healthy environment for plants, animals, and yourself!
- Eutrophication - This is the process where lakes change because of an overabundant supply of nutrients. Excess phosphorus, nitrogen, and other materials in the lake cause rapid growth of aquatic weeds and algae. This growth leads to the buildup of muck on the bottom, and the replacement of sport fish, such as bass and walleye, by rough fish like carp. No wonder eutrophic lakes are said to "age." The natural process can be slowed or even reversed by proper land use management practices and the maintenance of properly designed sewage treatment systems. It is important to remember that once a lake has become severely degraded, even the most costly methods may not be able to restore it. Full and active participation in your local lake property owners association is the best way to see that everyone cooperates in protecting the lake from overenrichment of nutrients (eutrophication).