The Coastal Nonpoint Source Pollution Control Program in Massachusetts - The Problem

It all adds up! Everything people do that releases contaminants to the air, soil, or water has the potential to become nonpoint source (NPS) pollution. When each of these individual actions is taken together, the impacts on coastal waters are staggering. Many national studies point to NPS pollution as the largest single factor contributing to coastal water pollution.

NPS pollution occurs when rain water and snow melt run over farm fields, city streets, timberland, lawns, and other surfaces. Contaminants, such as soil sediments, nutrients from fertilizers and sewage, and chemicals from pesticide use and other sources, are picked up as the water runs over the ground and through the soil. The contaminated rain water and snow melt ultimately flow directly into a surface water body (such as the ocean, a river, or a lake), or they seep into groundwater or enter a drainage system, which eventually carries the contaminants to a surface water body.

Unlike point source pollution from industrial pipe discharges and other direct sources, the sources of NPS pollution are extremely diverse and widespread. Virtually every activity that adds something to the environment or takes something away can cause NPS pollution. For example, adding fertilizers and pesticides to a field can cause NPS pollution when rain water washes excess nutrients and chemicals into surrounding water bodies. In addition, removing trees from a forested area can cause NPS pollution by exposing soil, which can then be more easily washed into surrounding water bodies when it rains. Even the most common everyday actions, such as cleaning the house, driving to work, and walking the dog, can contribute to NPS pollution. Although each one of these activities alone has only a small impact, the combined impacts of the activities of millions of people add up to water pollution problems.

In the past, the NPS pollution that resulted from human activities and natural processes (such as erosion and plant and animal decay) was not significant enough to impair the ability of aquatic ecosystems to handle these contaminants. As human activities have increased, however, the quantity and diversity of NPS pollutants entering water bodies have also increased. Today, in many areas, the levels of NPS pollution have adversely affected the health and productivity of coastal ecosystems. In addition, NPS pollution can prevent these water bodies from meeting water quality standards, which means that people cannot use the water for certain purposes, such as drinking, shellfishing, or swimming. Continued NPS pollution can also alter the quality of wildlife habitats, which can reduce plant and animal populations.

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Published: October 1994