Stormwater Management

What is Stormwater Management?

Stormwater Management is the process of controlling the runoff from precipitation (i.e, rain or snow) that flows off of impervious surfaces like parking lots, driveways, sidewalks, and rooftops. Unchecked stormwater flows from these hard surfaces to streets and gutters, which carry the untreated runoff to rivers and lakes.

Stormwater runoff is often worsened by human activities, and can contain nitrogen and phosphorus pollutants from fertilizers, pet and yard waste. Because stormwater flows over hard surfaces directly into a water body or storm drain, there is no opportunity for soil and plants or a water treatment facility to filter out pollutants. Urban and suburban areas produce much more stormwater runoff due to the high amount of paved and hard surfaces.

During periods of heavy rainfall or snowmelt, some wastewater systems are designed to occasionally overflow and discharge excess untreated sewage directly to nearby streams, rivers or other water bodies. These discharges are known as combined sewer overflows and are common in many cities nationwide.

Stormwater Pollution

Stormwater pollution refers to many types of harmful materials that are carried by rainwater and wash water through the storm drain system to our creeks and lakes. Ultimately this pollution reaches rivers and lakes because it makes its way through their tributaries. While water we use in our homes and businesses drains to a treatment plant or septic system, stormwater and anything else dumped or spilled outdoors flows into the storm drain system and directly to our waterways. Stormwater is not cleaned or treated in any way.

Stormwater pollution has many sources. One of the most common is the illicit disposal or spilling of wastes directly into storm drains, like pouring used motor oil or paint directly into a storm drain or ditch. Another common source of pollution is sediment from disturbed areas such as construction sites.

Pollutants also enter storm drains when it rains; rain runs off roofs, streets, parking lots, and other paved and impervious surfaces and flows into the nearest storm drain, picking up impurities along the way. Rain, as well as waters from hoses and sprinklers, carries detergents from car washing in addition to sediment, pesticides, herbicides, and fertilizers to the storm drain. From the storm drain, water flows directly into the nearest waterway-garbage, toxins, sediment and all.

Green Infrastructure

Green infrastructure can be used to address stormwater runoff and sewer overflow problems. Green infrastructure works by slowing down the runoff, spreading it out over the land, and slowly soaking it into the ground, or in some cases reusing the water onsite. Green infrastructure is also sometimes referred to as low impact development. These techniques also help to remove pollutants from runoff, buy allowing plants to filter out pollutants as the water slowly infiltrates into the ground. Some examples of green infrastructure techniques include rain gardens, pervious pavement, rain barrels, and green roofs.