About the City Surface Water Utility

About the Washington State Department of Ecology (Ecology) Permit
The City of Mill Creek is issued a permit from the 
Washington State Department of Ecology (Ecology) so that the City can discharge stormwater into pathways, such as natural streams like North Creek, that drain out of our city limits. 

This permit is titled the Western Washington Phase II Municipal Stormwater Permit.  For short, the permit is frequently called the "Ecology permit", the "MS4 permit", the "NPDES permit", and similar names.

Ecology's permit is issued in compliance with the federal Clean Water Act through the National Pollutant Discharge Elimination System (NPDES).  The Clean Water Act required all municipal agencies across the United States to take steps toward reducing pollution to natural receiving waters from stormwater runoff.  NPDES has also built relationships with the federal Endangered Species Act in many areas, including ours, for protection of salmon and other endangered and threatened species impacted by salmon habitat loss.

Mill Creek is a Phase II municipality/public agency, which means we are issued the same Phase II permit issued to all municipalities with a population under 100,000.

Each Ecology permit has a duration of five (5) years, though this can be extended by Ecology under select circumstances.  The current Ecology permit became effective August 1, 2019, and will expire in 2024.

The Ecology permit provides requirements for a wide range of required compliance activities by the City as a whole, from individual private property owners to the City Surface Water Utility described below

Compliance with the permit include multiple activities associated with each of the following:

  • Operations and Maintenance
  • Administration and Financial Management
  • Public Education and Outreach
  • Strategic/long-term Planning, including ongoing system mapping
  • Public Stewardship/Volunteering
  • Water Quality Sampling and Tracking, particularly discharges to North Creek from both the storm system and natural tributaries such as Penny Creek
  • Pollutant Source Identification and Elimination
  • Development/Redevelopment Oversight and Permitting
  • Documentation in detail of all permit activities and obligations to Ecology

About the City of Mill Creek Surface Water Utility
The City created a public enterprise utility called the Surface Water Utility in 1999 in order to manage stormwater within the City and maintain citywide compliance with the current Ecology permit requirements.  This Surface Water Utility manages stormwater runoff in order to meet the following goals:

  • Control storm water runoff and erosion
  • Prevent flooding
  • Protect water quality
  • Rehabilitate stream and drainage corridors to benefit salmon and wildlife habitat
As a public enterprise utility, the Surface Water Utility is primarily funded by annual stormwater fees paid by each City resident and business.  These fees are collected by the City and used for all activities and programs required to comply with the City's Ecology permit.  Fulfilling the Ecology permit conditions and requirements represent necessary expenses that are included within the overall financial planning of the utility enterprise, particularly to achieve and maintain long-range sustainability.

Public Utility Operation and Maintenance

Mill Creek's Surface Water Utility operates and maintains all the publicly-operated stormwater conveyance (e.g. pipes, surface channels, catch basins, etc.) and stormwater facilities (e.g. ponds, vaults, etc.) that are located either within the public right-of-way and/or on City-owned property (e.g. City parks, City Halls, etc.). This consists of 38 different detention and water quality facilities, including ponds, vaults, and detention pipes, nearly 5,000 catch basins, and 50 miles of pipe.

Additionally, the Surface Water Utility provides advice and guidance to property owners responsible for operating and maintaining stormwater conveyance and facilities within their properties.  This includes the conveyance and facilities maintained by neighborhood associations. 

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

Here is a 2017 map of stormwater drains.

Additional Surface Water Utility Program Responsibilities
The City Surface Water Utility is also responsible for tasks associated with the following:

  • Financial management of the Surface Water Utility program, including management of enterprise funding from stormwater fees and external (typically State) grant funding opportunities
  • Annual and milestone documentation and reporting to the Washington State Department of Ecology
  • Strategic long-term planning for the City stormwater system, including planning for changing needs and/or regulatory requirements
  • Review and update, when necessary, the City of Mill Creek Municipal Code to meet the regulatory requirements of the Ecology permit
  • Pollution source identification and elimination, including detecting and eliminating illicit discharges and connections to the stormwater system
  • Implement, permit, and enforce the use of development standards related to stormwater management for private and public developments and redevelopments, including the use of low impact development (LID) stormwater management methods
  • Manage Surface Water Utility-related capital improvement projects and programs by the City, including the Aging & Failing Infrastructure program
  • Provide public outreach and educational materials appropriate to our City through website updates, social media, in-person events, and similar means