STANWOOD — Mayor Sid Roberts remembers when he got the call in 2021, only two weeks after being sworn into office.
The 4-mile-wide mound of dirt responsible for holding back Skagit Bay from drowning hundreds of acres of farmland and downtown Stanwood had broken.
Fortunately, a hunter had noticed the crack forming in the dike, allowing people to react quickly and plug the hole.
Three years later, construction is beginning on a new deployable floodgate, the latest step to protect Stanwood residents from water danger all around them.
The new floodgate will be located near the Highway 532 overpass close to Marine Drive. This spot is a particularly vulnerable one where the Stillaguamish River has historically reached major flood stage, usually near Silvana, and water makes it way down to Stanwood, said City Administrator Shawn Smith, a former city engineer.
“In the years past, we’ve used sandbags and/or just piled up dirt to block that road off,” Smith said. “This will eliminate the need for using sandbags or dirt, which will allow city staff to install this flood wall in a matter of minutes.”
Heavy rains and snowmelt from the mountains have threatened Stanwood. The city lies in a 100-year floodplain only 2 feet above sea level in places.
“If there are heavy rains, like in Granite Falls, we get all that water,” Roberts said.
Manufacturers are in the process of making the wall, with hopes of completing the project by early next year. The total cost is estimated to be just under $433,000.
The floodgate will include a 30-foot channel built across the road with intermediate columns mounted into a steel base plate and anchored in concrete. When the gate is needed, plates will be put between the column, so it will take just minutes to block the road, Smith said.
The city, in cooperation with BNSF Railway, hopes to build another floodwall over the railroad tracks next to the road, Smith said.
“It costs them thousands of dollars when we close their tracks — shutting down all that train commerce,” he said, adding another major benefit of the floodgate is the shortened time to reopen the road after flooding dangers subside.
In addition to the floodgates, another project aims to increase the effectiveness of drainage through Irvine Slough, just south of Highway 532.
“When the Stillaguamish River experiences significant flood events, Irvine Slough and the lowlands south of state route 532 are inundated with floodwaters that are trapped behind the Stillaguamish River levees,” Stanwood city engineer Alan Lytton said. “The larger flood events can overtop Larson Dam and inundate Irvine Slough west of the dam.”
When completed, the project will direct excess water directly into the Irvine Pump Station or through a pump station to the Stillaguamish River.
The construction of the extra pump and the rerouting for stormwater to get there has been completed. Designs for the new pump station that will send water directly to the Stillaguamish River are being wrapped up.
Correction: A previous version of this story misstated where the floodgate is based on inaccurate information from the city.
Eliza Aronson: 425-339-3434; eliza.aronson@heraldnet.com; X: @ElizaAronson. Eliza’s stories are supported by the Herald’s Environmental and Climate Reporting Fund.
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