What is Stormwater?

Stormwater is rainfall, snowmelt, or any precipitation, that is not absorbed into the soil. It runs off rooftops, over sidewalks, down street curbs and across parking lots, eventually entering our local streams, Woodin and Mill Creeks.

Stormwater run-off is highly regulated by the Washington State Department of Ecology (ECY).  

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Managing Stormwater Run-Off

The city's stormwater drainage system is the managed infrastructure that collects, detains and treats stormwater run-off.

The system is designed to ensure that stormwater run-off does not contain pollutants when it reaches local streams in compliance with with strict ECY regulations.

Stormwater drainage rates were established in 2000 to provide revenue to meet ongoing and expanding ECY / NPDES (National Pollution Discharge Elimination System) requirements for managing stormwater run-off.   View the many components of the system below and the city's NPDES report.

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Publicly Owned Stormwater Facilities
The city owns and is responsible for maintaining over 90 stormwater facilities, like the pond pictured above. Maintenance, conducted 2 to 4 times a year on each facility, includes litter pick-up, mowing, weed eating and tree removal.

Inspection of Privately Owned Facilities
 As required by the WA Department of Ecology (ECY), the city inspects all private stormwater facilities (like the swale pictured above - there are about 100 in the city) and works with property owners to ensure the facilities are in compliance with ECY regulations.

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Catch Basins & Curb Inlets
There are over 2,600 catch basins and curb inlets within the city's stormwater drainage system. Per current ECY requirements, each one is inspected every 2 years.  

Infrastructure Design & Construction
The City is responsible for the design and construction of the stormwater infrastructure. Like sewer and water infrastructure, most components are located below the surface.  There are over 31 miles of conveyance pipe and culverts.

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Erosion Control
The city regularly conducts inspections to ensure that erosion control practices are appropriate and in compliance with ECY regulations.

Stormwater Facility Maintenance
Aging stormwater facilities may require reconstruction (removing trees and silt and replanting grasses) in order to provide the elements necessary to filter and treat water before it is released into our waterways.

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Investigating Illicit Discharge
Illicit discharge is the release of contaminants into the stormwater system. The city is required to investigate and report incidents involving illicit discharge.

Stormwater - Comprehensive Planning

Comprehensive Planning for Stormwater Management

During the 2019-2024 Permit cycle, the City will delineate basin boundaries and catchments (sub-boundaries) and prioritize basins in need of protection.  The City will develop short and long term plans to address impairments and develop a proposed implementation schedule and budget for at least one high priority basin.

Stormwater - Source Control Program

Source Control Program  (Business Inspections)

During the 2019-2024 Permit cycle, the City will adopt an ordinance requiring application of source control best management practices, develop an inventory of businesses and inspect 20% of the businesses annually.

Stormwater Outfalls
There are over 190 outfalls into creeks and wetland that the City is required to map and inspect. 12% of the outfalls are inspected annually.

Stormwater System Mapping

Municipal Stormwater System Mapping

The City has an ongoing program for mapping stormwater catch basins, manholes, storm facilities and pipes.

Stormwater - Monitoring and Assessment

Monitoring and Assessment

The City annually pays into funds for regional status and trends monitoring, effectiveness monitoring and source ID studies.


You Play an Important Role

Residents and businesses play an important role in protecting our streams and rivers.  See our Stormwater Education page for information on how everyday activities affect our surrounding waterways and the steps you can take to minimize harmful impacts.