Private Stormwater Facility Inspections

The City of Seattle is issued a National Pollutant Discharge Elimination System (NPDES) Permit by the Washington State Department of Ecology to be in compliance with the Federal Clean Water Act. The permit requires that all development be reviewed to control or treat stormwater prior to entering the City’s drainage system. SPU conducts maintenance inspections to ensure that these systems continue to operate as designed to protect private property, City infrastructure and the environment.

What is the inspection process?

  • Notification: A notification letter is mailed to the property owner. The inspection will be conducted within 30 days of the date of the letter. If the owner would like to be present, or if access to the property is restricted, please contact the Inspector to schedule an appointment.
  • Maintenance: Shortly after the inspection, the property owner will be sent a report with the inspection results. If the system requires maintenance or repairs, the report will include a checklist with details, a property map, and a Drainage Contractor List (pdf). Contractors on the list have agreed to certain expectations in working with Seattle property owners regarding maintenance of their systems. View the expectations (pdf).
  • Certification: When the work is completed, the property owner is responsible for returning the completed checklist with the Contractor’s invoice (if applicable) to the Inspector. The Inspector may return to verify the work.

How often will the system be inspected?

The discharge point of your site determines the inspection frequency of your drainage system. For sites that discharge to our lakes, streams and creeks, the current inspection frequency is every 2 years. For sites that discharge to the sewer treatment plant, the inspections are less frequent. 

The City’s goal is to establish an appropriate inspection frequency for each site based on characteristics such as the stormwater system, property type, etc. The inspection frequency will vary for each site, but will likely be somewhere between 2 – 10 years.

What are my responsibilities as the owner?

As the owner of the system, you are ultimately responsible for the inspection of the system. However, SPU performs the inspection to ensure proper maintenance is being performed and the system is functioning as designed. If the system requires maintenance and the maintenance is not conducted in a timely manner, SPU will initiate its progressive enforcement policy to gain compliance.

Stormwater systems are required to be maintained by the Seattle Municipal Code (SMC 22.800-808):

SMC 22.807.090, Responsibility for Maintenance and Inspection: “The owner and other responsible party shall maintain drainage control facilities, source controls and other facilities as required by this subtitle and by rules adopted hereunder to keep these facilities in continuous working order.”

The Stormwater System Maintenance Inspection Program is part of the City’s overall Stormwater Management Plan, developed to comply with the requirements of the City’s NPDES permit. Maintenance standards are provided and enforced under the City’s Stormwater Code, Chapter 22.800 – 22.808 and associated Director’s Rules.