Issue Profile
Nonpoint Source Pollution
- March 1998. (207) 287-3901
Background
Clean water is important to everyone in Maine, and one of the keys to understanding water quality is to understand the concept of watersheds. A watershed is the land area - much like a bowl - in which water is collected. As we all know, water flows by gravity down hill, first forming small streams which flow into larger streams into lakes, rivers and eventually the ocean. In Maine, we all live in a watershed, whether we're in Kittery or Fort Kent.
The activities that take place in watersheds affect water quality. Over the past 20 years Maine's industries and municipalities have done a great job cleaning up industrial pollution and sewer discharges. Today, most of our water pollution comes from stormwater. Every time it rains, the rainwater washes off driveways, roofs, parking lots, roads, agricultural fields, construction sites, forestry operations, and other surfaces carrying with it contaminants to our streams, lakes, ocean and groundwater. This type of pollution is known as nonpoint source pollution (NPS).
How serious is nonpoint source pollution?
NPS is the number one threat to the waters of the state of Maine and the nation. Maine has 2,500 Great Ponds, and almost 10%, or 234 lakes, are known to have water quality problems. Many of these lakes are experiencing "cultural eutrophication", or increased algal growth, that reduces water clarity and dissolved oxygen for fish habitat. There are 230 closed shellfish areas ( 269,387 acres "off limits" to harvesting) and 724.5 miles of rivers, streams and brooks that fail to fully support all their designated uses. NPS pollution is the major reason for most of these water quality problems.
Nationally, the U.S. Environmental Protection Agency estimates that a full 60 percent of all pollution sources are nonpoint.
Who is responsible for nonpoint source pollution?
Since water pollution is caused by land use activities, each of us can be contributing to nonpoint source pollution without even being aware of it! Therefore, everyone must try to prevent or control nonpoint source pollution. Clean water starts with each one of us!
DEPLW-60-A98
How can nonpoint source pollution be controlled?
Over the years many groups and agencies have developed methods for controlling NPS pollution. These methods are called Best Management Practices, or BMPs. They can be as simple as seeding and mulching a site, or as complicated as engineered structures like nutrient control basins. In either case, the goal is to prevent pollutants from reaching the water.
Types of Nonpoint Pollutants and Their Impacts
|
Pollutant
|
Nonpoint Source |
Impacts |
Bacteria |
Livestock, pet waste, septic systems, and boat discharge |
Introduces disease bearing organisms to surface water and ground water, resulting in shellfish bed closures, swimming restrictions, and contaminated drinking water |
| Nutrients (phosphates & nitrates) |
Fertilizers, livestock, pet waste, septic systems, suburban & urban development, and soil erosion |
Promotes algae blooms and aquatic weed growth which can deplete oxygen, increase turbidity, and alter habitat conditions. |
| Sediment (Soil) |
Construction, driveways, ditches, earth removal, dredging, mining, gravel operations, agriculture, road maintenance, and forest operations. |
Increases surface water turbidity which in turn reduces plant growth and alters food supplies for aquatic organisms, decreases spawning habitat and cover for fish, interferes with navigation and increases flooding risk. |
| Toxics & Hazardous Substances |
Landfills, junkyards, underground storage tanks, hazardous waste disposal, mining, pesticides and herbicides, auto maintenance, runoff from highways & parking lots, boats and marinas |
Accumulates in sediment posing risks to bottom feeding organisms and their predators, contaminates ground and surface drinking water supplies; some contaminants which may be carcinogenic mutagenic and/or teratogenic can bioaccumulate in tissues of fish and other organisms including humans. |
| Airborne Pollutants (i.e., acid rain, nutrients & metals) |
Automobile and industrial emissions |
Reduces pH in surface water which alters habitat and reduces natural diversity and productivity; increased nitrogen may enhance eutrophication of coastal waters. Mercury accumulates in fish tissue threatening bald eagles and people. |
This table was adopted from Massachusetts DEP's NPS Fact Sheet #1.
Can individuals make a difference?
You bet. In fact, by making simple changes in our daily lives we can make a tremendous difference in the quality of Maine's water resources. Here are just a few ways you can help:
Soil: Try to keep exposed soil areas to a minimum and seed and mulch disturbed areas as soon as possible (within a week). Properly shaping roads, road ditches and driveways will also help reduce soil erosion. Planting a vegetative buffer down slope of your home and yard can act as a filter to collect and remove sediments and nutrients from stormwater.
Fertilizers: Fertilizers contain nitrates and phosphates which, in abundance, cause algae blooms that can lead to fish kills. Avoid overuse of fertilizers, and do not apply them right before it rains.
Pesticides: Many household products made to exterminate pests are also toxic to humans, pets, wildlife, fish, small aquatic organisms and plants. If at all possible, use natural pest control methods, but when a commercial pesticide is necessary, follow all label directions carefully and never over use.
Household Hazardous Products: Many common household products (paint thinners, moth balls, and drain & oven cleaners, to name a few) contain toxic ingredients. When improperly used or discarded, these products are a threat to public health and the environment. Never pour hazardous products down any drain or toilet. Do not discard with regular household trash. Use natural and less toxic alternatives whenever possible.
Motor Oil: Motor oil contains toxic chemicals that are harmful to humans, pets, wildlife and fish. Never dump used motor oil down a storm drain or on the ground. Recycle all used motor oil by taking it to a service station or local recycling center. (One gallon of oil can contaminate one million gallons of water.)
Pet and Livestock Waste: Animal wastes contain bacteria and viruses that contaminate shellfish and cause the closing of swimming areas. Pet owners should pick up after their pets and dispose of the wastes in the garbage or toilet. Livestock owners should work with their local Soil and Water Conservation District Office to develop a manure management plan.
Septic Systems: An improperly working septic system can contaminate groundwater and create public health problems. Avoid adding unnecessary grease and solids to your septic system. Inspect your septic system annually and pump it out at least every 3 to 5 years.
Boat Discharges: Dumping boat sewage introduces disease-causing bacteria and viruses into the water and adds nitrates and phosphates that can trigger algae blooms. Boat owners should always use marine sanitation devices or pump-out facilities at marinas.
Litter: Place litter, including cigarette butts and fast food containers, in trash receptacles. Never throw anything down storm drains. Recycle as much as possible.
How can I get additional information on NPS pollution?
For more information on what you and your community can do to reduce nonpoint source pollution, call or write the Bureau of Land and Water Quality, at the DEP office nearest you:
Central Maine Regional Office Eastern Maine Regional Office
17 State House Station 106 Hogan Road
Augusta, ME 04333-0017 Bangor, ME 04401
(207) 287-3901 (207) 941-4570
Northern Maine Regional Office Southern Maine Regional Office
1235 Central Drive 312 Canco Road
Presque Isle, ME 04769 Portland, ME 04401
(207) 764-0477 (207) 822-6300
Or check out our web site at: www.maine.gov/dep
Other sources of information and assistance include your regional planning agency, the local Soil and Water Conservation Districts, and the State Planning Office (207) 287-3261.
