STANWOOD — The city aims to dredge tons of material from Irvine Slough to protect downtown against flooding.

The proposal is to remove up to 3,000 cubic yards of sediment from a 2,500-foot-long stretch. It’s part of the maintenance for the slough system, which handles stormwater runoff. The city’s plans have been submitted to state and federal agencies.

Dredging would be done annually for up to 10 years, according to a public notice from the U.S. Army Corps of Engineers and the state Department of Ecology. They are among the agencies that must review the plans.

The removed material would be disposed off-site and away from the water, according to the project application. Work would be done each summer for a few weeks during July or August.

The goal is to remove sediment and debris that have accumulated in the slough, to create more space for water. Irvine Slough is a drainage channel with a pump station. It parallels Highway 532, south of downtown Stanwood. The downtown area falls entirely within the floodplain of the Stillaguamish River.

“The slough is the primary feature that provides conveyance of stormwater from the city of Stanwood to the Stillaguamish River, avoiding flooding within the city,” public works director Kevin Hushagen wrote in a January letter to the Army Corps.

When the river breaks its banks, floodwater in the slough can cause stormwater to back up into downtown streets, according to the city. That is something planners and city leaders aim to remedy through other projects that could take years to complete.

Meanwhile, there is regular maintenance such as dredging. The plan is to clear the channel to its original dimensions, removing dirt, rock, plant matter and other debris that have built up over time.

The work area would stretch from the pump station at the mouth of the slough to about 92nd Avenue NW.

Kari Bray: 425-339-3439; kbray@heraldnet.com.