The National Pollutant Discharge Elimination System is a permit based water quality program implemented under the authority of the Federal Clean Water Act, enacted by Congress in 1972.  The primary goal of NPDES is to reduce the amount of pollution that reaches streams, lakes, wetlands, oceans, and all other water bodies by regulating stormwater runoff. Visit the US Environmental Protection Agency and WA Department of Ecology for more information on the federal and state programs.

Kent complies with NPDES by maintaining a current Western Washington Phase II Municipal Stormwater Permit administered by the Washington State Department of Ecology. The permit has 5 major components that the City is required to focus on and they are described under each section below:

• Education and Outreach
• Public Involvement
• Detect and Eliminate Pollution
• Construction and Development
• Operations and Maintenance

Education and Outreach

The City strives to inform and connect with citizens on stormwater issues to instill general understanding and appreciation for our vital water resources that will hopefully reduce and eliminate pollution in our city's and region's waterways. The ultimate goal is to affect change through YOU... because only you can change your decisions and behaviors that contribute to negative impacts on water quality.

We work with Kent schools, neighborhood groups, and businesses to provide education opportunities and awareness. If you are interested in having someone talk and meet with you or your group, please contact us. 

What you can do today!

• Get more information - you're already here so you're off to a great start!
  •  Check out a 5 minute video What is stormwater and why is it important? by King County that explains stormwater and its effect on the area.
• Figure out how stormwater flows onto, around, and off of your property.
• Learn about ways to prevent pollution from coming into contact with stormwater.
• Talk to your family, friends, neighbors, coworkers, etc... about stormwater issues such as picking up after pets or storing, using, and disposing of common household products that contain chemicals and hazardous materials.
  • Kid Friendly Links:
    • Freddy the Fish Teaches about Stormwater
    • A Ground Water Education
• Stay on the lookout for spills or stormwater pollution and report it!
  • For emergencies call 911
  • For urgent spills call the Spill Hotline at 253-856-5600 or submit online report 

Public Involvement

The city welcomes and values citizen engagement in stormwater management and the City's Stormwater Management Program (SWMP) Plan. Public participation is needed in order for us to be successful in protecting and improving the quality of our precious water resources.

Ways that you can get involved and participate: 

• Review Kent's Stormwater Management Program (SWMP) Plan
• Review the annual Kent NPDES report 
• Attend, or watch online, the City Council and Public Works Committee Meetings 
• Contact us with questions, concerns, and comments at NPDES@KentWA.gov

Detect and Eliminate Pollution 

Everyone can identify and prevent pollution!

Through Illicit Discharge Detection and Elimination (IDDE) we all work together to protect and preserve our natural and built resources.

An illicit discharge is any release of a non-stormwater substance into the stormwater drainage system and/or waterways; substances such as common household cleaners, car fluids and wash water, paint, garbage, dirt, yard and pet waste. 

Through our 24-hour spill hotline 253-856-5600 and online reporting form we receive reports about spills and illicit discharges and/or connections. City staff respond promptly to spill reports in order to prevent pollution from entering stormwater drainage systems and waterways.         

Construction and Development 

All development and construction sites are required to use stormwater best management practices (BMPs). 

Examples of BMPs include:

• Not allowing track out of dirt onto roads
• Silt fencing to reduce runoff from site
• Catch basin filter bag inserts to stop sediment from entering the storm system
• Covering piles of dirt and loose materials
• Properly storing, using, and disposing of chemicals and all other materials

Click here for the brochure on single family home small projects erosion and sediment control.

Stormwater Pollution Prevention Plan (SWPPP)

Any development or construction site in Kent that disturb one acre of soils or greater are required to develop and submit a Stormwater Pollution Prevention Plan or SWPPP to the city. The SWPPP includes site specific BMPs for reducing or eliminating pollution in stormwater before it leaves the site. The SWPPP’s proposed BMPs must be reviewed prior to permit approval and are required to be continuously inspected during construction in order to reduce erosion potential on the site and to protect water quality.

A complete SWPPP will focus on 12 main elements that have the potential to affect stormwater and water quality. These 12 elements include:

1. Preserve Vegetation & Mark Clearing Limits
2. Establish a Construction Access
3. Control Flow Rates
4. Install Sediment Controls
5. Stabilize Soils
6. Protect Slopes
7. Protect Drain Inlets
8. Stabilize Channels and Outlets
9. Control Pollutants
10. Control De-Watering
11. Maintain BMPs
12. Manage the Project 

In addition to developing and implementing a SWPPP, all construction sites disturbing greater than one acre of soil are also required to conduct periodic inspections of their site to verify that the proposed BMPs are adequately protecting the site from erosion and sediment control issues. It is required that every construction site has a Certified Erosion and Sediment Control Lead (CESCL) who conducts the required inspections. A CESCL is a person who has current certification through an approved erosion and sediment control training program. The Washington State Department of Ecology approves these courses and keeps and updated list of current classes on their website.

Operations and Maintenance 

Kent Public Works Department is responsible for the operations and maintenance of the municipal separate storm sewer system (MS4).

Staff work diligently to operate and maintain Kent's MS4 for efficient conveyance, storage, and, in some cases, treatment of stormwater before it is discharged to surface or ground waters, to reduce localized flooding, decrease instances of erosion, and allow treatment processes to function properly.  

Your drainage utility fee helps pay for inspection, operation, and maintenance of all publicly owned and/or operated stormwater conveyance and facilities including:

• 18,000+ catch basins 
• 350+ detention/retention ponds and bio-retention swales
• 50 stormwater flow control and treatment facilities (vaults and filter vaults)
• 300+ miles of pipes and roadside ditches
• Stormwater pump stations
• Dams
• Culverts and channels
• Creeks
• Wetlands
• Lakes
• Green River in Kent

It takes a considerable amount of time and staff resources to accomplish inspections and maintenance to ensure a full-functioning MS4. To view the annual storm division work plan go to Work Plans.

Examples of operations and maintenance activities:

• Respond to and clean up spills and illicit discharges
• Clear debris from roadside ditches, inlets, outlets, and culverts to prevent and alleviate flooding
• Inspect catch basins, flow control, and treatment facilities
• Install and restore structures, pipes, culverts, ditches, etc...
• Remove sediment and debris from structures, pipes, culverts, swales, ditches, etc...
• Manage vegetation in ponds, bio-retention swales, wetlands, ditches, etc...

City of Kent Maintenance Standards for Stormwater Facilities

• Common Facilities (Catch Basins, Ponds, Bioswales, and Vaults)
• Less Common Facilities (refer to Appendix A of the King County Surface Water Design Manual)