About Stormwater

In 1987, Congress changed the federal Clean Water Act by declaring the discharge of stormwater from certain industries and municipalities to be a point source of pollution. Due to this change, certain stormwater discharges now require a National Pollutant Discharge Elimination System (NPDES) permit to discharge to surface waters. The U.S. Environmental Protection Agency (EPA) gave the Department of Ecology (Ecology) the authority to implement these permits in Washington State.

The EPA stormwater regulations establish two phases (Phase I and Phase II) for the stormwater permit program. Phase I was established in 1990 and requires municipalities with populations of 100,000 or greater to implement a stormwater management program as a means to control polluted discharges from stormwater systems. Phase II was established in 1999, and expands the requirement for stormwater permits to all municipalities located in urbanized areas and to construction sites between one and five acres. The cities of Asotin, Clarkston, and urbanized parts of Asotin County are considered to be part of the Clarkston Urbanized Area. To see a map of the 2000 Census Defined Urbanized Areas for the Lewiston-Clarkston area, click here.

Because this is a requirement under the federal Clean Water Act, a stormwater program must be implemented. If the cities and county elect not to develop a program locally, Ecology will develop one for us. We feel it is better to have local control and involvement in the program. Additionally, failure to implement a program could result in fines, legal actions, and potential loss of future funding sources.

To see the Eastern Washington Phase II Permit click here.

Why Is Stormwater Important?

Today, we know that urban stormwater runoff is the largest remaining contributor of water quality pollution to the urban waterways of the United States. The problem is magnified when development occurs without addressing stormwater pollution, which puts additional stress on the environment. When land is converted from its natural state to one of parking lots, buildings, lawns, streets, and sidewalks, rainwater that once soaked into the ground now flows over the hard, or impervious, surfaces and becomes urban stormwater runoff. The water picks up pollutants such as dirt, fertilizers, pesticides, oil, and bacteria on its way to the nearest storm drain or creek. Unlike sewage, which is collected and treated at a wastewater treatment plant, anything that flows into a storm drain empties directly into the nearest stream or creek, normally without any treatment.

Pollutants in stormwater come from a variety of places, including our cars, streets, parking lots, lawns, construction sites, industrial areas, agricultural areas, pet waste, etc. Because the sources of pollutants are so widespread, the runoff is termed “nonpoint source (NPS)” pollution. Many of our daily activities contribute to NPS pollution and can take their toll on water quality. Typical stormwater pollutants include sediment from construction sites and bare ground, oil and grease from cars and parking lots, fertilizers and pesticides from our lawns, toxic metals from cars, and bacteria from animal waste.