Stormwater Management Program

The Public Works Department has prepared a Stormwater Management Program (SWMP) as required by the National Pollutant Discharge Elimination System (NPDES) Phase II Municipal Permit (the Permit) issued by the Washington State Department of Ecology (Ecology). This program was implemented to improve the quality of water discharged from the city’s storm drainage system into the Green River via Newaukum Creek and into the White River via Boise Creek. The permit requires the city to submit Annual Reports on its stormwater activities and annual updates to its SWMP Plan for future stormwater activities. These documents can be found at the links provided at the bottom of the page.

Stormwater Management Action Plan (SMAP)

The City of Enumclaw and over 80 other cities and counties in Western Washington developed a SMAP to help protect and improve local receiving water quality and habitat. The SMAP is a watershed-scale approach to stormwater management, taking into consideration land use and how the landscape is developed to protect the water quality of streams and wetlands. Through the process, receiving water conditions, uses, and influence from stormwater within the two basins serving Enumclaw (Boise and Newaukum Creek) were evaluated and 15 catchment areas within those basins prioritized based on multiple water quality factors. The highest-ranking catchment areas (Cedar and Farman) were combined with the largest agricultural catchment area (Battersby) to create the Watercress catchment area for which the SMAP was developed. Click on this link to view the current Watercress Stormwater Management Action Plan.

The Watercress SMAP includes consideration for several different strategies including stormwater capital projects/retrofits, fish passage/habitat improvement projects, land acquisition, land use management adjustments, enhanced public stormwater drainage system maintenance, prioritized source control inspections, and other stormwater management actions.  The initial SMAP was completed in March 2023. Updates to the SMAP are provided when additional information or feedback becomes available that would improve the plan. To provide input on the types of projects or actions you would like to see implemented or for other inquiries on the SMAP, please contact our Stormwater Program Manager (        

Ecology Manual

To mitigate for impacts associated with stormwater runoff, the city requires that stormwater management practices be designed, constructed, operated and maintained in accordance with the Stormwater Management Manual for Western Washington (SWMMWW) prepared by Ecology. The current SWMMWW can be accessed from the Ecology website.

Low Impact Development (LID)

Low Impact Development is a stormwater management strategy that strives to mimic natural pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design. In March 2017, as required by the Permit, the city approved an ordinance requiring implementation of LID principles and LID best management practices (BMPs) on all new development and redevelopment projects where feasible. In addition to the SWMMWW, information on LID can be found from the following resources:

Illicit Discharge Reporting

If you are aware of a spill (illicit discharge) into a stormwater system, ditch or waterway please contact:

  • Public Works Department: Monday to Friday, 9 a.m. - 4:00 p.m.
    • (360) 825-3593 or (360) 825-5541
  • Enumclaw Police Department: After hours and holidays
    • (360) 825-3505

For Spills and other environmental issues outside the city limits contact the Department of Ecology Northwest Regional Office at Ecology Spills.

Private Stormwater Facility Maintenance

The City of Enumclaw requires property owners to inspect and maintain stormwater systems on their private property (including but not limited to backyard drains, catch basins, inlet drains, conveyances, treatment BMPs/facilities, and flow control BMPs/facilities). Inspections of private stormwater facilities shall be conducted at minimum annually and maintenance performed in accordance with the Maintenance Standards for Drainage Facilities found in the SWMMWW (Chapter 4 of Volume V). It is important that property owners maintain these systems to prevent pollutants from entering the storm drainage system and surface waters of Enumclaw. For more information on actions that can be taken to help prevent pollutants from entering the storm drainage system see Protecting Water Quality.

Property owners of new or redevelopment projects subject to Minimum Requirement #9: Operations and Maintenance of the SWMMWW, are required to have on site or within reasonable access to the site, a copy of the approved operation and maintenance manual for their private stormwater facilities. A log of maintenance activities shall be kept and made available to the city upon request.

Stormwater Management Program Reports

The City will continue to provide information to residents and businesses regarding stormwater management. In addition, city staff will review the effectiveness of public outreach efforts based on the Stormwater Management Program.

The Stormwater Management Program Plan is updated at least annually. Click on the link below to view the current Stormwater Management Program Plan and latest annual report.