Stormwater is water from rain or melting snow that does not soak into the ground. Stormwater in a forest, meadow, or other natural environment usually soaks into the ground, i.e., infiltrates, or is filtered as it flows along the ground and over native vegetation. When forests and meadows are developed, they are commonly replaced with impervious surfaces such as houses, buildings, roads and parking lots. Impervious surfaces prevent stormwater from soaking into the ground, which create excess stormwater runoff. Stormwater can become polluted when it runs off streets, lawns, farms, and construction and industrial sites if there are fertilizers, dirt, pesticides, oil and grease, or other pollutants in its path. When polluted stormwater is left untreated, it enters our rivers, lakes, and coastal waters and can cause water quality impairments.
Stormwater pollution is one of the leading causes of water pollution nationally. Unlike pollution from industry or sewage treatment facilities, i.e., point source pollution, which is caused by a discrete number of sources that are easily identified, stormwater pollution is caused by the daily activities of people everywhere. Because of this, the responsibility of managing stormwater falls on everyone. All across New Hampshire, communities, businesses and property owners are experiencing the challenge of managing stormwater to protect the state’s water resources and to balance the need for a healthy environment with the need for social and economic growth.