Nonpoint source pollution, often referred to as stormwater runoff or urban runoff, is water pollution that cannot be traced to a specific origin or starting point. For example, when it rains, stormwater runoff washes silt, car fluids, pesticides, fertilizers, leaves and litter into storm drains and into nearby lakes and streams. Soil erosion from lawns and construction sites pollute our waterways with silt. Every time it rains, these substances can make their way to our lakes, streams and rivers. Septic systems that are not performing optimally can release nutrients which move downward through the soil into the water table.
This process causes over half or the water pollution problems in the United States (U.S. EPA).
Did you know that…
- At least 50% of the water quality problems in the U.S. result from NPS pollution (U.S. EPA).
- Five quarts of used motor oil can create an oil slick two football fields in size.
- Yard fertilizer runoff from residential areas is estimated to be responsible for one third of the excess nitrogen polluting our waterways.
- The first inch of runoff generally carries 90% of the pollution from a storm (Florida Department of Environmental Protection).
- Storm drains do not always go to sewage treatment plants, they often lead directly to bodies of water.
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Fertilizers
Fertilizers contain large amounts of nutrients such as phosphorus and nitrogen and other toxic materials that are harmful. When it rains, these chemicals wash into nearby lakes and streams. Then, instead of fertilizing our yards, we "fertilize" plant life in the lakes, upsetting the delicate balance of chemistry that naturally exists, and causing an overgrowth of aquatic plants. As the water system loses this balance, a cascade of negative effects on water quality occur. Our local lakes are connected to the underground aquifer, the source of local drinking water. If each of us takes a few water-friendly steps in our yard practices, together we will make a positive change in the quality of our water.
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Pet Waste
The volume of pet waste is more than can be naturally absorbed into the environment. Pet waste contains bacteria that can cause diseases in humans if it contaminates streams, lakes and ponds. The U. S. Environmental Protection Agency reports that just 100 dogs in a 20 square mile watershed can contribute enough bacteria, nitrogen and phosphorus in 2 to 3 days to temporarily close a bay to swimming and shell fisning. Dogs present a special problem. Built to eat almost anything, dogs have as especially large number of intestinal bacteria to digest that wide variety of food, about 23 million bacteria per gram of waste. There are products on the market that allow you to pick up after your pet without getting your hands dirty. It's best to regularly clean up after your pets. |
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Urban runoff
In urban areas, roads, bridges, parking lots and roofs of buildings prevent rainwater from slowly percolating into the ground as it has in the past. Water falls on these surfaces, accumulates and runs off in amazing volumes and velocities. As the water flows, it picks up a variety of pollutants and carries them into nearby lakes and streams. Sediment from development and new construction, oil, grease and toxic chemicals from automobile brakes and exhaust, nutrients and pesticides from gardening, and viruses and bacteria from poorly maintained septic systems are examples of pollutants generated in urban areas. By slowing the flow of water from yards and neighborhoods, water will have more time to soak into the soil and more naturally filter contaminants.
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Hazards around the Home
Just by washing a car in the driveway, cleaning products flow into stormwater drains. Phosphates in the soap act as fertilizers to algae in lakes and waterways. Dumping motor oil, antifreeze, gas or any other chemicals down these drains is also harmful. The U. S. Environmental Protection Agency claims that 17 million gallons fo fuel, mostly gasoline, are spilled each year while refueling lawn equipment. That is more than all the oil spilled by the Exxon Valdez in the Gulf of Alaska. Leaking septic tanks and clogged drainfields have also become a problem. Sewage includes anything that goes down the drain in our home from the toilet, sink, shower and kitchen. Many of the chemicals that we use in everyday household cleaning can contaminate drinking water and be poisonous to aquatic life if introduced into waterways or groundwater.
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Agriculture
Agricultural activities that cause pollution include confined animal facilities, grazing, plowing, pesticide spraying, irrigation, fertilizing, planting and harvesting. The major agricultural pollutants that result from these activities are sediment, nutrients, pathogens (bacteria and viruses), pesticides and salts.
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