Drainage Facility Inspection and Maintenance Program
Snohomish County contains a large network of publicly- and privately-owned storm drainage facilities, such as detention ponds, underground vaults, catch basins, and biofiltration swales. In order for these facilities to function properly, they need regular maintenance. The Surface Water Management (SWM) Drainage Facility Inspection and Maintenance Program helps ensure that both public and private drainage facilities are regularly maintained by their owners. The ultimate goal of the program is to help reduce flooding of private property and public roads, improve water quality, and protect aquatic habitat. In 2009, this program was expanded to comply with recent changes to the County’s National Pollutant Discharge Elimination System (NPDES) permit.
 Purpose of the Program
- Inspect privately owned storm drainage facilities that are subject to the NPDES permit;
- Identify facilities that need to be cleaned or repaired;
- Ensure that facility owners maintain these facilities so that they function properly; and
- Help facility owners understand and meet their maintenance responsibilities.
Inspections of Storm Drainage Facilities
In order to meet federal and state mandates related to the NPDES permit, the County must inspect public and private storm drainage facilities for compliance with the Snohomish County Water Pollution Control Code (SCC 7.53) and the Snohomish County Drainage Manual. County-owned facilities must be inspected and maintained annually. Privately-owned facilities must be inspected by the County at least once before February 2012, and at least once every five years after that.
For each storm drainage facility, a SWM inspector will:
- Check the facility to determine if it is in good working order;
- Send the facility owner a notice that states whether the facility is compliant with the County Drainage Manual, and if not, provide a list of deficiencies to be corrected; and
- Conduct a follow-up inspection to determine if required maintenance and repair work was completed.
Learn more about the inspection process.
For lot owners in single-family residential plats with drainage facilities regulated by the NPDES permit, the County is providing one-time maintenance assistance, funded by SWM service charges.
Note: Certain types of property owners who maintain their drainage facilities may be able to qualify for a reduction in their annual SWM service charge. Please see the SWM billing page for more information.
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Under SCC 7.53 and the County Drainage Manual, owners of storm drainage facilities are legally responsible for maintaining the facilities so that they function properly over the long term.
While the County Drainage Manual contains the maintenance requirements, the County has provided additional maintenance guidelines to property owners with the Stormwater Facility Maintenance Handbook.
In many cases, maintenance will consist of removing sediment, tree roots, or trash from the facilities. In other cases, more extensive maintenance or repair work will be needed. Typically, the maintenance or repair of a storm drainage facility requires special equipment and skills, and should be carried out by a licensed contractor.
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County maintenance
crew cleaning underground
catch basin. |
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