What is Nonpoint Source Pollution?
Nonpoint source pollution (NPS) occurs when rainfall, snow melt, or irrigation runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, and coastal waters or introduces them into ground water. Imagine the path taken by a drop of rain from the time it hits the ground to when it reaches a river, ground water, or the ocean. Any pollutant it picks up on its journey can become part of the NPS problem. NPS pollution also includes adverse changes to the vegetation, shape, and flow of streams and other aquatic systems.
NPS pollution is widespread because it can occur any time activities disturb the land or water. Agriculture, forestry, grazing, septic systems, recreational boating, urban runoff, construction, physical changes to stream channels, and habitat degradation are potential sources of NPS pollution. Careless or uninformed household management also contributes to NPS pollution problems.
The most common NPS pollutants are sediment and nutrients. These wash into water bodies from agricultural land, small and medium-sized animal feeding operations, construction sites, and other areas of disturbance. Other common NPS pollutants include
- pathogens (bacteria and viruses),
- toxic chemicals,
- animal wastes
- and heavy metals.
Beach closures, destroyed habitat, unsafe drinking water, fish kills, and many other severe environmental and human health problems result from NPS pollutants. They also spoil the beauty of healthy, clean water habitats. Each year the United States spends millions of dollars to restore and protect the areas damaged by NPS pollutants.
Specific examples of nonpoint source pollution are provided in the following sections, which detail nonpoint source pollution as it occurs in the mountains, plains, and canyons of the Intermountain West.
While much of the western plains may seem flat for as far as the eye can see, here, too, rainwater and snow melt run off the land to settle in low-lying areas and water basins. Water, whether from irrigation or precipitation, carries with it on its downhill journey the refuse of our lives and lifestyles - from our farmlands and construction sites as well as from our very own streets and yards.
The dry, red-rock canyonlands of the West are notorious for their torrential rainstorms. These heavy downpours bring swift and sweeping runoff waters to wash the dusty landscape clean. But it's not just the dust, the soil and the sediment this runoff carries - it's everything else in its path.
To address these problems, Congress amended the Clean Water Act (CWA) in 1987 to establish the section 319 Nonpoint Source Management Program because it recognized the need for greater federal leadership to help focus state and local nonpoint source efforts. Under section 319, states, territories, and tribes receive grant money which support a wide variety of activities including technical assistance, financial assistance, education, training, technology transfer, demonstration projects, and monitoring to assess the success of specific nonpoint source management projects.
Nonpoint source pollution should not be confused with point source pollution, which is governed under a different section of the Clean Water Act. By point sources, EPA means discrete conveyances such as pipes or constructed ditches. All point sources discharging pollutants into waters of the United States must be authorized under a National Pollutant Discharge Elimination System (NPDES) permit.
To find out more about Region 8's National Pollution Discharge Elimination Program, visit the NPDES web site .