Nonpoint Source Pollution

Controlling Nonpoint Source Pollution

Sediment fences such as this are used to control erosion, trap large materials, filter sediment from rainwater, and slow runoff. Click on image for larger view.

While research, monitoring, and assessment look at the larger environmental effects of nonpoint source pollution, taking measures to stop pollution before it begins is also essential for controlling the problem. This is especially true in coastal communities. According to a NOAA Coastal Population Trends Report, about 153 million people lived in coastal areas in 2003. This is 53 percent of the total U.S. population. Between 1980 and 2003, the total coastal population increased by 28 percent, or 33 million people (Crossett et al., 2004.) If coastal populations continue to grow, the chances for more nonpoint source pollutants such as nutrients, sediments, pesticides, and other toxic chemicals to enter waterbodies via runoff increases.

Even though the exact locations of nonpoint source pollution cannot be identified, scientists know that certain environments and operations produce a high volume of pollution. Experts have developed systems to reduce and even eliminate pollution from these places. Listed below are some strategies that urban and suburban areas, agricultural operations, forestry operations, and marinas use to decrease nonpoint source pollution.

Similar to sediment fences, retaining fences are used to prevent contaminants from entering aquatic environments. Click on image for larger view.

Urban and Suburban Areas

• Buffer strips are strips of grass located between and around impervious paving materials such as parking lots and sidewalks, and a body of water. The buffer strip absorbs soil, fertilizers, pesticides, and other pollutants before they can reach the water.

• Retention ponds capture runoff and stormwater. Sediments and contaminants settle out of the water when they are trapped in the retention pond.

• Constructed wetlands are a recent innovation in which an area is made into a wetland; the land is then used to slow runoff and absorb sediments and contaminants. The constructed wetland also provides habitat for wildlife. 

• Porous paving materials are used in parking lots and highways. The porous pavement allows rainwater and stormwater to drain into the ground beneath it, reducing runoff. In some cases, there is also a stone reservoir underneath the pavement to allow filtration of the water before it reaches the groundwater. 

• Sediment fences, or knee-high black fabric fences, are often used at construction sites to trap large materials, filter sediment out of rainwater, and slow runoff.

• Grass planting and laying of straw around construction sites help reduce runoff and associated nonpoint source pollution.

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Agricultural Operations

• Buffer strips are planted located between a farm field and a body of water. The buffer strip absorbs soil, fertilizers, pesticides, and other pollutants before they can reach the water.

• Conservation tillage involves leaving some crop residue from a previous harvest while planting a new crop. Less erosion occurs because the field is not plowed, and nutrients or pesticides are more likely to stay where they are applied.

• Crop nutrient management involves applying fertilizers sparingly to prevent excess nutrient runoff. Prior to the growing season, farmers test the fields to ensure that nutrients are applied only as needed.

• Beneficial insects can be used to control agricultural pests, reducing the need for pesticides. Common predators include ladybugs, praying mantises, and spiders, which feed on aphids, mites, and caterpillars. These natural predators help control infestations on valuable crops such as corn, soybeans, and tomatoes.

Forestry Operations

• The location and design of roads and skid trails (temporary pathways used to shuttle logs out of the forest) are carefully planned prior to any logging operations. Skid trails are designed to follow the contour of the land and reduce erosion. 

• Buffer strips are maintained between logging operations and nearby streams, lakes or rivers.

  Pump-out stations at marinas such as this one allow boaters to empty their sanitary systems without contaminating the water. Click on image for larger view.

• Trees are replanted after logging to allow for regrowth and less erosion.

Marinas

• Shutoff valves on fuel pumps on docks help limit spillage into the water.

• Pump-out stations at marinas allow boaters to safely empty their sanitary systems without dumping wastes into the water.

• Trash is placed in appropriate waste containers.

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