Surface Water

Under a permit issued by the State Department of Ecology, the City of Mill Creek Surface Water Utility (SWU) manages stormwater runoff in order to:

  • Control storm water runoff and erosion
  • Prevent flooding
  • Protect water quality
  • Rehabilitate stream and drainage corridors to benefit salmon and wildlife habitat

Drainage Facilities
Mill Creek operates and maintains all the drainage facilities located within the public roadways and on city owned property. This consists of 38 different detention and water quality facilities, including ponds, vaults, and detention pipes, more than 2,900 catch basins, and 50 miles of pipe.

Property owners are responsible to operate and maintain drainage systems located on private property.

Here is a 2017 map of stormwater drains.

SWU Responsibilities
In addition to facility operation and maintenance, the city SWU is responsible to:

  • Detect illicit discharges
  • Enforce development standards
  • Implement new technologies such as low impact development
  • Manage drainage related capital improvement projects
  • Provide educational materials

The annual SWU fees paid by residents and businesses are used for all these activities, as well as general compliance with the conditions of the Ecology NPDES permit.


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Phone: 425-551-7254

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