Boulevard Park flooding: the city's record, and what it means inside a house

Boulevard Park became part of Burien on 1 April 2010, when the southern part of North Highline was annexed. The flooding the city later set out to fix was not new. By the city's own description, it was nuisance flooding for many years before it worsened into significant flooding of several properties and structures, every year.

Part of the reason was ownership. Much of the neighborhood's stormwater ran through a primarily privately owned system rather than a city one. Under Burien's municipal code, drainage the city doesn't own — down to roof downspout drains and driveway drains — is maintained by the person responsible for the property, up to the point where it connects to the city's system. A chain of private drainage is only as good as its weakest link, and when a link fails in heavy rain, the water collects at the lowest building.

The city completed a flooding study in 2022. In February 2023 the City Council directed staff to find the money to act on it.

The flooding had a second layer, and it is the one that matters most inside a house.

Parts of Boulevard Park were still on private septic systems into the 2020s. In its environmental filings for a new sewer extension there, Valley View Sewer District reported that many of those systems had passed their 50-year life expectancy and were failing routinely. The flooding made it worse: owners reported septic failures every year, because stormwater ponded over drain fields and septic tanks.

The district planned public sewer for about 75 homes, with their septic systems to be decommissioned once connected. That sewer extension is the project the city used for its drainage work — under a 2025 agreement, the stormwater improvements were built as part of it. The flooding and the septic failures were tackled as one project.

Valley View's website lists further sewer extensions in the area as under way or planned.

Rain coming through a wall starts out clean. Water that has sat over a failing septic system doesn't. A failing system can push sewage back up through a house's drains or up to the surface of the yard, and floodwater that pooled over it should be treated as contaminated — the same category as a sewer backup.

That changes the job. Porous materials the water touched — carpet and pad, drywall above the waterline, insulation under the floor — usually come out rather than being dried in place. Everything that stays gets cleaned and disinfected before drying starts. Keep children and pets out of the affected rooms, and out of the crawl space if the water got under the house.

If you can't tell whether the water is clean, treat it as contaminated until someone who can test it says otherwise.

The stormwater work near the 1200 block of South 124th Street finished in early 2026. City staff are monitoring the drainage to see whether it did what it was built to do, and whether more is needed. A third phase, further downstream, is under consideration with federal funding through the Army Corps of Engineers. It is not funded or scheduled.

The city hasn't said the flooding is over, and it hasn't said it continues. Its Boulevard Park Flood Reduction Project page carries the current status.

If it's coming up through a toilet, shower or floor drain and the house is on public sewer, call your sewer district first. They'll check whether the blockage is in their line. The three Burien sewer districts are listed on our homepage, and the City of Burien's utilities page has a map of which one serves your address.

If the house is on septic, the sewer district isn't the call. A septic service deals with the tank. What came into the house is a cleanup job — call (206) 813-0805.

If it's floodwater from outside, or a pipe inside the house, shut off the water at the main if that's where it's coming from, stay clear of anything electrical, and call (206) 813-0805.