Private Stormwater System Maintenance Program

What are stormwater systems? 



Stormwater is rain or snow that falls on our roads, parking lots and roof tops. It picks up harmful bacteria from pet waste, oils, dirt and metals on its way to the nearest storm drain, creek, lake or Puget Sound.  Stormwater systems are designed to slow down and remove some of the harmful pollutants from the water before it travels back into our waterways.  Our stormwater runoff does not enter a sewer-type treatment plant to be cleaned and therefore, is the leading cause of pollution in our state’s waterways. 

A stormwater pond is one component of some stormwater systems.

Stomwater Pond v2_storage capacity-01

What is your responsibility?



Some neighborhoods and businesses have private stormwater systems that collect, convey, treat and recycle the stormwater from their property.  These private systems are generally owned, inspected, and maintained by the Homeowners' Association (HOA) or commercial property owner.

It is important for all stormwater systems to be inspected yearly and maintained. Regular maintenance ensures your system is functioning properly and can help to save you money in the long run. Commercial property owners, homeowners, or homeowner's associations are responsible for providing regular maintenance of privately owned ponds, storm drains, pipes, and other drainage system components that serve the property or subdivision. 

You can use our Private Stormwater System Manual and Inspection Checklist to help you complete your yearly inspection.  It’s important to keep records of your yearly inspection checklist and any maintenance performed. You may need to hire a private contractor to help with some of the maintenance. 

What is the county’s responsibility?



The county is responsible for stormwater facilities within the public right-of-way and on public property.  We regularly inspect and maintain about 4,217 catch basins, 27 treatment and control systems, and stormwater pipes and ditches along 938 miles of County roads.  Our inspectors are always happy to help you with questions about your private system responsibilities. We can even schedule a site visit and help you complete your inspection.

Virtual Workshop Videos

To help you understand and evaluate the private stormwater system maintenance needs within your development or property, we created a new virtual workshop complete with short videos and a comprehensive manual. Scroll down and watch the videos to start learning now!

If you are interested in speaking with one of our stormwater system inspectors after you review the videos, please fill out the request form at the bottom of this page. We are happy to provide a free inspection of your stormwater system and a report with our maintenance recommendations.

Video #1: What is Stormwater?

Learn the basics about stormwater in our community and why stormwater facilities are important to maintain. 

Video #2: Understanding System Components

A breakdown of the main components that make-up a stormwater system and the possible maintenance associated with each component. 





Video #3: Good Practices Around Your Property


A review of the best management practices that help to prevent stormwater pollution and keep your system functioning properly.

Video #4: Conveyance System

Learn more details about the stormwater system components that help move water through your system and how to properly maintain them.


Video #5: Pond Maintenance


Learn more details about stormwater ponds and proper maintenance. 

Questions, comments, or site-visit requests?
Click here to contact one of our inspectors for more help.

If this is an emergency, call 911.

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