Nonpoint Source Pollution - Background
Introduction
There are two types of pollution that pose great threats to Maine's water quality: point source pollution and nonpoint source pollution, also known as stormwater runoff. Point source pollution can be traced back to a specific source such as a discharge pipe from a factory or treatment plant. Since there is a direct source in this case, the pollution is much easier to identify.
Just the opposite is true for nonpoint source pollution. Many times it cannot be traced back to a specific source, rather it it often comes from a number of diffuse sources within a watershed (all the land area that drains into one waterbody). Stormwater runoff is water that doesn't soak into the ground during a rain storm and flows over the surface of the ground until it reaches a stream, lake, estuary, or the ocean. Stormwater runoff often picks up polluting hitchhikers such as soil, fertilizers, pesticides, manure, and petroleum products. These pollutants may originate from places like farm fields, driveways, roads, golf courses, and lawns located within a watershed.
There are five major topics to consider when discussing stormwater runoff
1. Soil
2. Phosphorus
3. Bacteria
4. Toxics
5. Thermal Pollution
More introductory information about Nonpoint Source Pollution
Related page: Learn how to prevent stormwater runoff.
