Stormwater Management Program

This document has been prepared to meet the City of Des Moines’ Western Washington Phase II Municipal Stormwater Permit requirement for written documentation of the City’s Stormwater Management Program (SWMP). 

The City’s SWMP is intended to reduce the discharge of pollutants from the City’s Municipal Separate Storm Sewer System (MS4) to the maximum extent practicable (MEP), meet Washington State, All Known, Available and Reasonable methods of Treatment (AKART) requirements, and protect water quality.  This goal will be accomplished by the inclusion of all permit SWMP components and implementation schedules into the City’s existing SWMP.

Where the City is already implementing components called for in this permit, the City will continue those actions or activities to the existing extent required, regardless of the schedule called for in this document.

The City will implement an ongoing program for the gathering, tracking, maintaining and using information to evaluate the SWMP development, implementation and permit compliance and to set priorities.  Beginning no later than January 1, 2009, the City will begin to track the cost of development and implementation of each component of the SWMP. 

LID Stormwater Code Updates

To meet State and Federal Law, The City of Des Moines is required to update its stormwater code, incorporating Low Impact Development (LID) “as the preferred method” of stormwater management within the City by December 31, 2016.

These code changes will require developers to take new and/or additional actions at project sites. (Each project that submits a complete application for a building permit, clearing and grading permit, subdivision, etc., after 12/31/2016 will be required to comply with the new stormwater code)

What this means for your project: Prioritized LID Practices

Incorporating LID into Stormwater Code will require development projects that create 2,000 square feet of hard surface area or disturb more than 7,000 square feet of land to: 
  1. Conduct LID Site Assessment prior to site design to determine how to minimize runoff and to evaluate soil suitability for infiltration. 
  2. Increase protection of undisturbed native soil, trees, and other vegetation. 
  3. Infiltrate runoff on-site to the degree feasible through the use of LID stormwater facilities such as rain gardens or bioretention facilities.

What is LID and why use it?

Low Impact Development techniques imitate the natural processes that help rainfall absorb into the ground, instead of running into pipes that drain to streams and lakes. LID features such as rain gardens, bioretention facilities, and permeable pavements, treat and retain stormwater at the source. Using these techniques helps protect fish and wildlife and preserve the health of our lakes, rivers, streams and Puget Sound, as community assets.

Contact Water Quality Specialist, Tyler Beekley, for more information regarding the LID, City’s stormwater code changes, and how you can get involved.