South Park Pump Station

Project Description

Improving chronic flooding and drainage issues in South Park
SPU is building a pump station which will send stormwater runoff to the Duwamish Waterway during high tide events when the storm drain system cannot drain by gravity. In doing so, the pump station will reduce flooding on roads that have a formal stormwater collection system (including catch basins and inlets). This project will work in unison with the South Park Drainage and Roadway Partnership project to reduce flooding in the South Park lower industrial basin.


636 and 640 S Riverside Drive

What's Happening Now?

The project team is currently finalizing project design.

Community Benefits

When complete, this project will pump stormwater from South Park's lower industrial basin into the Lower Duwamish Waterway, preventing water from backing up in the pipes during high tide and causing flooding.

Community Engagement

SPU is committed to providing timely information and updates on project activities. Updates may be available in multiple formats: the website, emails, and one-on-one briefings. Check back for more information about the project.
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2017 - 2019
  • Design, permitting and real property work for pump station
  • Anticipated start of construction


Seattle Public Utilities is currently working on two other stormwater projects in South Park's lower industrial basin to reduce flooding and improve water quality in the Lower Duwamish Waterway:

  1. A South Park Drainage and Roadway Partnership project to construct streets and a drainage system to improve chronic flooding and drainage issues.
  2. water quality facility to treat stormwater from the storm drain system before it flows into the Duwamish Waterway.

The northern industrial and residential area of South Park experiences chronic flooding for three reasons:

The main drainage pipe to the Lower Duwamish Waterway is underwater during high tide.
When it rains during high tides, the main pipe in 7th Ave S that flows to the Duwamish Waterway cannot drain out to the river, and water backs up in the drainage system. Rain falling in the lower areas of the basin cannot flow out, and water in the main pipe can sometimes flow back out of inlets and catch basins, flooding the neighborhood. A pump station will allow the main pipe to drain during high tides and relieve flooding in areas that have a drainage system in place.

Not all streets in the area have a drainage collection system.
Additional conveyance improvements will not be fully effective until the pump station is installed so that the pipes can drain at high tide. When additional roadway drainage is built, it will connect to the main pipe in 7th Ave S and the pump station will allow the system to drain when the tides are high.

Many private properties in the basin do not have drainage pipes connected to the public drainage system.
Some properties are lower than the street or are located along streets where there is no existing collection system. In these areas, individual property owners may want to make site improvements to connect to a public drainage system in the street once one is available.

Budget & Funding

The project is supported in part with funding from the King County Flood Control District.

King County Flood Control District logo 

Project Documents