Surface Water Management Division
County Inspection and Maintenance of Storm Drainage Facilities
SWM regularly inspects both public and private storm drainage facilities throughout unincorporated Snohomish County as part of a larger effort to prevent and control pollution associated with stormwater runoff. This inspection program is required by the County’s NPDES permit and primarily applies to facilities that detain and remove pollutants from stormwater, such as detention ponds, catch basins, detention vaults, and biofiltration swales. In the first step of the inspection process, the County conducts a site inspection to determine whether a storm drainage facility needs maintenance. Then, depending on who is responsible for the facility, the County will either perform the maintenance or require the private owner to do so, as further described below.
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County Facilities
The first category of inspections involves County facilities. Snohomish County is currently responsible for maintaining all storm drainage facilities that are located on:
- County road rights-of-way,
- County-owned property, and
- Private property where an easement gives the County responsibility for maintaining the drainage system.
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The frequency with which the County inspects and maintains storm drainage facilities depends on whether or not the facilities are regulated by the County’s NPDES permit. For those facilities that are regulated by the permit, the County typically performs inspections and any required maintenance on an annual basis. If the inspection history indicates that the facilities do not require maintenance every year, then the interval between inspections can be increased to a more appropriate time period, such as every two or three years. For those facilities that are not regulated by the NPDES permit, the County performs inspections on a less frequent interval due to budget constraints.
Snohomish County is currently responsible for the maintenance of hundreds of detention and water quality facilities (e.g., detention ponds, underground vaults, biofiltration swales, etc.) as well as thousands of catch basins. The specific number of facilities changes each year due to annexations and new County projects. The maintenance of these facilities is typically performed by the County’s Department of Public Works (DPW) staff.
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Residential Storm Drainage Facilities
The second category of inspections involves residential storm drainage facilities located:
- In single-family residential plats, and
- On private property with no drainage easement dedicating maintenance responsibility to the County.
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For these facilities, the property owners are legally responsible for any necessary maintenance. Facility owners can be a single property owner, a group of owners, or a homeowner’s association.
In 2009, in response to new requirements in the County’s NPDES permit, the County began to inspect storm drainage facilities subject to the permit in single-family residential plats to determine whether they need maintenance or repair. The County will inspect each of these facilities at least once during each five-year NPDES permit cycle, with the current permit cycle ending in February 2012.
Although the County is not responsible for maintaining private residential storm drainage facilities regulated by the NPDES permit, the County is providing one-time maintenance assistance, funded by Surface Water Management (SWM) service charges, for facilities located in plats with detached homes. This one-time assistance will be performed at no additional cost to the facility owners and will include all maintenance actions required by the County's Drainage Manual. For more information call 425-388-3464 or send an e-mail.
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Other Types of Private Facilities
The third category of inspections involves storm drainage facilities located on:
- Other types of private properties, such as commercial and industrial properties, condominiums, mobile home parks, schools, hospitals, fire districts, and utility districts, where the facilities have no drainage easement dedicating maintenance responsibility to the County.
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For these facilities, the owners are responsible for any necessary maintenance.
In 2009, in response to new requirements in the County’s NPDES permit, the County began to inspect privately-owned storm drainage facilities that are regulated by the permit in order to determine whether they need maintenance or repair. The County will inspect each of these facilities at least once during each five-year NPDES permit cycle, with the current permit cycle ending in February 2012.
Based on the results of the inspections, facility owners will be provided with a list of required maintenance actions for their storm drainage facilities. Depending on the type and extent of maintenance needed, facility owners will be given a specific timeframe in which to complete the work. The most common time frame will be one year, although for certain activities the time frame will be as little as 30 days or as much as two years (see Frequently Asked Questions - link text to subpage 2 - for more details). Following the completion of maintenance activities, County staff will re-inspect the facilities to ensure that the required work was done.
In October 2009, SWM sent a letter and brochure to property owners in this category that are located within unincorporated Snohomish County and that are believed to have storm drainage facilities regulated by the County’s NPDES permit. The County plans to hold two public meetings in October 2009 to provide additional information for these property owners and to answer questions.
Letter to Property Owners (PDF)
Informational Brochure (PDF)