Water that falls during a rainstorm or melting snow is stormwater. But once it falls from the sky, where does all that water go? The way that water moves through the landscape and the ways that people change this movement can determine whether water is a welcome resource or a nuisance or even a hazard.
Movement of water through a typical forested watershed:
Movement of water in an area developed with buildings and roads:
Credit: Curtis Hinman, Washington State University, Pierce County Extension, 2005
In developed areas such as Kirkland, we have many hard surfaces such as roadways and rooftops that do not allow water to soak into the ground. Lots of water running over hard surfaces, also called stormwater runoff, can lead to flooding, stream channel damage and water quality problems.
The runoff from drizzling or pounding rain picks up fertilizers, pesticides, soaps and other pollutants from the ground and transports them to the nearest storm drain and eventually to local creeks, wetlands and Lake Washington. This pollution contaminates our waterways and can harm or kill fish and other wildlife.
Stormwater runoff quickly flows downstream from developed land during the rainy season. As a result, this water can cause localized flooding of homes and businesses and overwhelm streams, wetlands and wildlife habitat. This flooding harms streams and wetlands and destroys habitat needed for fish and other wildlife.