Stormwater

Stormwater is water that originates from rain, including snow and ice melt. Stormwater can soak into the soil (infiltrate), be stored on the land surface in ponds and puddles, evaporate, or runoff. Most runoff is conveyed directly to nearby streams, rivers, or other water bodies (surface water) without treatment.

Overview

Stormwater is a major component of the water cycle. It is considered one of the main ways water is cycled back to the ocean. In natural landscapes such as forests, the soil absorbs much of the stormwater and plants help hold stormwater close to where it falls. In developed environments, unmanaged stormwater can create two major issues: one related to the volume and timing of runoff water (flooding) and the other related to potential contaminants that the water is carrying (water pollution).

Stormwater Management

Stormwater management is the effort to reduce runoff of rainwater or melted snow into streets, lawns and other sites and the improvement of water quality, according to the United States Environmental Protection Agency (EPA). When stormwater is absorbed into the soil, it is filtered and ultimately replenishes aquifers or flows into streams and rivers. However, when heavy rainwater hits, ground saturated by water creates excess moisture that runs across the surface and into storm sewers and drainage ditches. It can also cause erosion and flooding.

Stormwater Runoff

Stormwater runoff is water from rain or melting snow that "runs off" across the land instead of seeping into the ground. This runoff usually flows into the nearest stream, creek, river, lake or ocean. The runoff is not treated in any way.

Stormwater Pollution

Stormwater pollution, also referred to as stormwater contamination, occurs when pollutants are washed into stormwater runoff during rain events. Common pollutants include sediment, nutrients (from lawn fertilizers), bacteria (from animal and human waste), pesticides (from lawn and garden chemicals), metals (from rooftops and roadways), and petroleum by-products (from leaking vehicles).

See Also

• Water Cycle
• Water Pollution
• Environmental Protection Agency