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.
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.
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
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
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
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.
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
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 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.
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 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.
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.
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.
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.
information on how you can help, contact your
State Water Quality Coordinator
Assisted Monitoring Program
County Cooperative Extension Officer (612) 374-8400
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.
Lawns - Green Lakes, Minnesota Lakes Association Water Quality
Newsletter, March/April 1999
Source Runoff Pollution from Roads, Highways and Bridges. EPA,
Office of Water, August 1995 (EPA-841-F-95-008a)
System Owner's Guide, University of Minnesota Extension Service,
publication number PC-6583-GO.