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; jgsanders@heraldnet.com.

Talk to us

More in Local News

News logo for use with stories about Mill Creek in Snohomish County, WA.
Mill Creek house fire leaves 1 dead

The fire was contained to a garage in the 15300 block of 25th Drive SE. A person was found dead inside.

Firefighters respond to a house fire Wednesday morning in the 3400 block of Broadway. (Everett Fire Department)
3 hospitalized in critical condition after Everett house fire

Firefighters rescued two people, one of whom uses a wheelchair, from the burning home in the 3400 block of Broadway.

The Walmart Store on 11400 Highway 99 on March 21, 2023 in in Everett, Washington. The retail giant will close the store on April 21, 2023. (Janice Podsada / The Herald)
Walmart announces Everett store on Highway 99 will close on April 21

The Arkansas-based retail giant said the 20-year-old Walmart location was “underperforming financially.”

Michael Tolley (Northshore School District)
Michael Tolley named new Northshore School District leader

Tolley, interim superintendent since last summer, is expected to inherit the position permanently in July.

Logo for news use, for stories regarding Washington state government — Olympia, the Legislature and state agencies. No caption necessary. 20220331
New forecast show state revenues won’t be quite as robust as expected

Democratic budget writers say they will be cautious but able to fund their priorities. Senate put out a capital budget Monday.

Everett Memorial Stadium and Funko Field on Wednesday, Sept. 2, 2020 in Everett, Washington. (Olivia Vanni / The Herald)
Drive to build new AquaSox ballpark gets $7.4M boost from state

The proposed Senate capital budget contains critical seed money for the city-led project likely to get matched by the House.

Dr. J. Matthew Lacy, Chief Medical Examiner for Snohomish County, answers preliminary questions from the state regarding his qualifications and experience as a medical examiner during the trial of Richard Rotter on Thursday, March 23, 2023, at Snohomish County Superior Court in Everett, Washington. (Ryan Berry / The Herald)
At Rotter trial, debate breaks out over graphic autopsy photos

A judge ruled some close-ups of Everett officer Dan Rocha’s injuries could be used, while others were ruled out.

Alderwood Middle High School Wednesday afternoon on December 8, 2021. (Kevin Clark / The Herald)
Student, 14, accused of attacking Lynnwood middle school teacher

The alleged assault occurred after lunch at Alderwood Middle School, according to the Edmonds School District.

A residential home is demolished at what will be the site of a new Lake Stevens Library on Wednesday, March 22, 2023 in Lake Stevens, Washington. (Sophia Gates / The Herald).
Site clearing begins for new Lake Stevens library

The initial work on Chapel Hill property brings dream of a new library closer to reality.

Most Read