Snohomish County must implement a variety of actions that limit or prevent pollution from entering and leaving the County’s storm drainage system. The County’s storm drainage system is the network of ditches, pipes, and catch basins that convey stormwater in county roadways and on county-owned property such as road maintenance facilities, the fairgrounds in Monroe, and Paine Field airport.
Each year, the County produces a SWMP document that describes these actions in more detail. The County also submits annual reports to the Department of Ecology. Each annual report is due on March 31 and covers the previous calendar year.
The permit refers to the set of required actions as a Stormwater Management Program (SWMP). The requirements of the SWMP include:
The County is also required to monitor stormwater discharges, treatment systems, and the effectiveness of pollution control programs.