public works

What is a Pollutant (Illicit Discharge)?

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When the City of Maple Valley incorporated, the City adopted by reference King County Code Title 9 
(MVMC 14.30.010) relating to surface water management. On October 20, 2008 portions of King County Code Title 9 were revised by King County (Ordinance 16264) to bring the County into NPDES compliance. This ordinance clearly defines "illicit discharge" in Section 9.12.025 of King County Code Title 9.

Some activities that may result in illicit discharges include:

  • Lawn watering with potable water
  • Dust control with potable water
  • Automobile and boat washing
  • Pavement and building washing
  • Swimming pool and hot tub maintenance
  • Auto repair and maintenance
  • Landscape maintenance (pesticides, herbicides, and fertilizers)

Resource Links

The following links provide information and materials to help minimize or eliminate stormwater and waterborne pollution.

Low Impact Development (LID)

Puget Sound Rain Gardens

Natural Lawn Care

Scoop the Poop

2009 King County Stormwater Pollution Prevention Manual: Best Management Practices for Commercial, Multifamily and Residential Properties

Department of Ecology - Washington Waters

Don't Drip and Drive: Fix That Leak!

Puget Sound Starts Here

Construction Stormwater General Permit


Fertilizers contain a small amount of phosphorous, and when improperly spread may run off into the City stormwater system and then into our lakes and streams. 

Lake Wilderness is suffering from too much phosphorous, and as a result, is experiencing toxic blue green algae blooms.

Use phosphorous free fertilizers to protect our lakes and streams. 


Contact Information 

Please contact the city's Public Works Department at (425) 413-8800 with your input concerning the City’s Stormwater Management Program or any stormwater related questions.

To report a spill, illicit discharge, or other water quality violation, please contact the City of Maple Valley at (425) 413-8800 during business hours or (206) 391-4212 after hours, weekends, or holidays and/or Washington State Department of Ecology at 1-800-645-7911.