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 Nonpoint Source Pollution
Nonpoint source pollution is pollution where the source cannot be traced to a single point. Sources can be things like roads, parking lots, fields, lawns and golf courses, and faulty septic systems. Pollutants can be sediment, fertilizer, pesticides, pet wastes, heavy metals and petroleum products. Often things that we might not normally consider pollution, like leaves or grass clippings, can find their way into our lakes and streams providing unwanted nutrients. Here is some information about non-point pollution and what you can do to prevent it.
Everyone is a lakeshore property owner because everyone lives in a watershed. Because of the storm sewer system, all urban property is essentially shoreline property because a lot of the water that lands on your lot eventually makes its way to a water body. Once runoff water makes it to the street, it enters the storm sewer system and then flows rapidly to the lake, wetland or stream without significant pollutant removal. It doesn't matter if a homeowner is next to a lake or two miles away the impact on the water resource is the same.

Here are some of the ways you can reduce your impact on surface waters:

1. Have your soil tested and follow soil test recommendations. Plymouth and other local city governments have passed ordinances regulating fertilizer use on lawns. Homeowners should be aware of any local regulations before applying fertilizer.

2. Any fertilizer spilled on sidewalks or roads should be immediately cleaned up by sweeping and removal. Do not wash fertilizer into gutters or lawns.

3. Water your lawn (<1") after fertilizing, but do not allow water to run off into street or lakes.

4. Never apply fertilizer to frozen ground.

5. When mowing lawns do not direct clippings into the street, sidewalk, or lake.

6. Do not over-water your lawn. Place a coffee can within the watering radius to monitor the amount of water dispersed. Avoid watering more than 1" at any time. Also, water in the morning to reduce the growth of molds and mildews on your lawn.

7. Clippings not left on lawn, leaves and other plant debris should be removed as soon as possible from street gutters, sidewalks, and driveways. This plant material can be composted, used in the garden as mulch, or disposed of through appropriate community services.

8. Grass clippings can be an effective way of recycling nutrients. Leaving clippings on the lawn provides nutrients for your lawn and greatly reduces the need for additional fertilizers.

9. For lakeshore owners, landscaping practices that force runoff to filter through the soil before entering the lake are suggested:
a. Leave a "buffer zone"- a strip of unmanaged grasses or natural vegetation to grow around the shoreline. This vegetation will help prevent soil erosion from the shoreland and will also remove and retain some of the nutrients that would otherwise enter the lake.
b. Construct and maintain a modified berm along the shoreline. This is best described as a slight hump in the ground that runs near parallel to the shoreline. This rise in the ground will serve as an obstacle to the rapid and direct nutrient-rich runoff into the lake.

10. Remove pet waste regularly from your lawn. Pet waste should either be buried (>100' from an open water source) or disposed of with your garbage. Pet waste contains nutrients and pathogens that can contaminate surface water.

11. Dispose of used oil, antifreeze, paints, and other household chemicals properly, not in storm sewers or drains. If your community does not already have a program for collecting household hazardous wastes, ask your local government to establish one.

Other source of nonpoint pollution

Sediment: Sediment is basically soil particles that were eroded from the land and transported to surface waters. Erosion is a natural process that usually occurs gradually because vegetation protects the ground. When land is cleared or disturbed to build a road or bridge the rate of erosion increases. When vegetation is removed and the soil is left exposed, it can quickly wash away in the next rain.

Erosion around bridge structures, road pavements, and drainage ditches can damage and weaken these structures. Sediment settles out of the water in a lake, stream, or bay onto aquatic plants, rocks, and the lake bottom. This sediment prevents sunlight from reaching aquatic plants, clogs fish gills, chokes other organisms, and can smother fish spawning and nursery areas. Other pollutants such as heavy metals and pesticides adhere to sediment and are transported with it by wind and water. These pollutants degrade water quality and can harm aquatic life by interfering with photosynthesis, respiration, growth, and reproduction.

Oils and grease: Oils and grease are leaked onto road surfaces from car and truck engines, spilled at fueling stations, and sometimes discarded directly onto pavement or into storm sewers instead of being taken to recycling stations. Rain and snowmelt transport these pollutants directly to surface waters.

Heavy metals: Heavy metals come from some "natural" sources such as minerals in rocks, vegetation, sand, and salt. But they also come from car and truck exhaust, worn tires and engine parts, brake linings, weathered paint, and rust. Heavy metals are toxic to aquatic life and can potentially contaminate ground water.

Debris: Grass and shrub clippings, pet waste, food containers, and other household wastes and litter can lead to unsightly and polluted waters. Pet waste from urban areas can add pathogenic microorganisms and nutrients to lakes.

Road salts: Road salts can be a major pollutant in both urban and rural areas. Snow runoff containing salt can produce high sodium and chloride concentrations in ponds, lakes, and bays. This can cause fish kills and changes to water chemistry.

Fertilizers, pesticides, and herbicides: If these are applied excessively or improperly, rainwaters from the green parts of public rights-of-way can carry fertilizers, pesticides, and herbicides. In rivers, streams, lakes, and bays, fertilizers contribute to algal blooms and excessive plant growth, and can lead to eutrophication. Pesticides and herbicides can be harmful to human and aquatic life.
Septic systems
A septic system that fails to treat sewage can also allow excess nutrients to reach nearby lakes and streams promoting algae and weed growth. Algal blooms and abundant weeds may make the lake unpleasant for swimming and boating, and can affect water quality for fish and wildlife habitat. As plants die, settle to the bottom, and decompose, they use oxygen that fish need to survive. Many synthetic cleaning products and other chemicals used in the house can be toxic to humans, pets, and wildlife. If allowed to enter a failing septic system, these products may reach groundwater, nearby surface water, or the ground surface.

Community action

Participate in clean-up activities in your neighborhood. Write or call your elected representatives to inform them about your concerns and encourage legislation to protect water resources. Get involved in local planning and zoning decisions and encourage your local officials to develop erosion and sediment control ordinances. Promote environmental education. Help educate people in your community about ways in which they can help protect water quality. Get your community groups involved.

For more information on how you can help, contact your

State Water Quality Coordinator
Citizen Assisted Monitoring Program
Citizen Lakes Monitoring Program

or Hennepin County Cooperative Extension Officer (612) 374-8400

Information sources

Metropoliton Council
Preventing Pollution Problems from Lawn and Garden Fertilizers, University of Minnesota Extension Service, publication number- FO-2923-GO.
Dos and Don'ts Around the Home, EPA Journal, November/December 1991, EPA-22K-1005.

Green Lawns - Green Lakes, Minnesota Lakes Association Water Quality Newsletter, March/April 1999
Controlling Nonpoint Source Runoff Pollution from Roads, Highways and Bridges. EPA, Office of Water, August 1995 (EPA-841-F-95-008a)

Septic System Owner's Guide, University of Minnesota Extension Service, publication number PC-6583-GO.


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