When it rains, stormwater picks up a wide variety of pollutants from surfaces such as parking lots, maintenance yards, sidewalks and streets. This contaminated runoff enters the storm drain system and in most cases, flows directly to our water bodies, including creeks, lakes and Puget Sound. The only way to avoid rainwater from coming into contact with these pollutants is to implement source control. Source control is the practice of preventing pollution at its source.

Stormwater management is required on all development to control or treat stormwater prior to entering the City’s drainage system. These stormwater systems prevent flooding and protect surface water quality by temporarily detaining the water during a storm and by trapping sediment and other pollutants. Although the property owner is ultimately responsible for regular maintenance and repairs of their stormwater system, SPU inspects these systems to verify the proper function and maintenance.

What is a stormwater system?

Your stormwater system may consist of a combination of catch basins, underground pipes, maintenance holes containing flow control structures and water quality treatment devices. The components can be technical and each component has maintenance standards to ensure that is it functioning at optimum capacity. The maintenance standards are outlined in the Stormwater Flow Control and Water Quality Treatment Technical Requirements Manual.