Irvine Slough is a drainage channel that parallels Highway 532 just south of downtown. (City of Stanwood)

Irvine Slough is a drainage channel that parallels Highway 532 just south of downtown. (City of Stanwood)

10-year, $11M project to end Stanwood flooding begins Monday

Stormwater in the downtown area often closes roads, delays transportation and causes property damage.

STANWOOD — In December, the Stillaguamish River flooded with winter rains. Its waters rose and poured into the Irvine Slough along Highway 532, then backed up underground pipes and into downtown Stanwood.

A similar event happens every few years, flooding the streets and sometimes homes and businesses.

Next week, the city begins a 10-year plan to end such downtown inundation.

Downtown Stanwood sits near where the Stillaguamish River meets Port Susan, and falls entirely within a federally designated floodplain. Irvine Slough is a drainage channel that parallels Highway 532 just south of downtown.

Stormwater runs downhill from town into Irvine Slough. When the Stillaguamish River overflows its banks, the slough and surrounding farmland flood. That floodwater closes flap gates between the city’s stormwater system and the slough, causing stormwater to back up into downtown streets.

“So all of downtown becomes essentially a bathtub,” city engineer Shawn Smith said.

Floods close roads, delay transportation, swamp yards and cause property damage, he said.

The problem led to talks of moving Stanwood’s City Hall and police station to higher ground.

To fix the issue, the city plans to redirect stormwater straight into the river, rather than the slough.

The plan will take place in six phases.

The first, which begins Aug. 31, will add a water pump right next to the Hamilton smoke stack. Water from the west end of downtown, near Twin City Foods and across Highway 532, will be rerouted to that pump instead of Irvine Slough.

Work should finish in early 2021. When it’s complete, Smith said that portion of downtown should fare better in any floods.

The entire project is estimated to cost about $11 million. The first phase will cost about $900,000, and is covered entirely by a $1 million state Department of Ecology grant.

Stormwater has backed up into downtown several times in the past decade, only skipping a few years, Smith said. But the floods may start happening more often, he said.

“With sea level rise and increased rain events, it is likely we will see an increase in the frequency of these events,” Smith said.

Julia-Grace Sanders: 425-339-3439;

Talk to us

More in Local News

Providence Regional Medical Center Everett. (Olivia Vanni/The Herald)
Providence nurse’s tearful plea shines light on short-staffed ER

The nurse described an overwhelmed emergency department, as staff have pleaded with the Everett City Council for hazard pay.

FILE - This 2003 electron microscope image made available by the Centers for Disease Control and Prevention shows mature, oval-shaped monkeypox virions, left, and spherical immature virions, right, obtained from a sample of human skin associated with the 2003 prairie dog outbreak. A leading doctor who chairs a World Health Organization expert group described the unprecedented outbreak of the rare disease monkeypox in developed countries as "a random event" that might be explained by risky sexual behavior at two recent mass events in Europe. (Cynthia S. Goldsmith, Russell Regner/CDC via AP, File)
Snohomish Health District hiring full-time monkeypox task force

The county is gearing up for more cases. The outbreak will be evaluated weekly to decide if a four-person team is merited.

Logo for news use featuring the municipality of Lake Stevens in Snohomish County, Washington. 220118
Body found in impounded car in Lake Stevens

In June, Bothell police impounded the vehicle. Last week, a Lake Stevens business found a body inside.

Logo for news use featuring the municipality of Lake Stevens in Snohomish County, Washington. 220118
California woman dies after motorcycle crash west of Lake Stevens

Kimberly Moore was the passenger on a motorcycle Friday morning. She died the next night. She was 53.

A view of the proposed alternative station location to Everett Station located east of the current BNSF rail tracks in downtown. (Olivia Vanni / The Herald)
Could light rail station under Pacific Avenue and over railroad work?

A group representing people around Everett Station wants Sound Transit to study the idea.

State Representative Robert Sutherland, left, gives a thumbs-up to passing drivers as he and a few volunteers wave flags and campaign signs along the side of State Route 9 on July 22, in Lake Stevens. Sam Low, right, talks with seniors on July 20 in Lake Stevens. (Sutherland photo by Ryan Berry / The Herald, Low photo by Kevin Clark / The Herald)
In GOP battle of Sutherland vs. Low, Democrats may tip the scale

The state lawmaker and Snohomish County council member are vying for a House seat. Democrats make up roughly 40% of the vote.

Food forum
Chocolate peanut butter Incredibles

These chocolate peanut butter bars are, as the name suggests, incredible.

SnoTown Brewing’s Frank Sandoval in 2019. (Aaron Swaney)
SnoTown Brewery owner charged with child molestation

Frank Sandoval conceded his conduct with a girl at his brewery was inappropriate, but he denied touching her sexually, charges say.

Head-on crash in Everett leaves man with life-threatening injuries

A two-vehicle collision in the 11600 block of Evergreen Way shut down southbound traffic Monday morning.

Most Read