The possibility of a major flood affecting the lower St. Croix River this spring has begun to spur action by local and state authorities. While the National Weather Service says there is a 80 percent chance of significant flooding, the city of Stillwater and others are beginning preparations to prevent damage to residents and business.

According to the National Weather Service’s North Central River Forecast Center, flooding could be as bad as it’s been for at least 20 years.

The flood potential for much of Minnesota into northwest Wisconsin is above normal this spring. The snow water content of the snow is quite robust for the 3rd week of March. Widespread water content amounts of 5 to 5.5 inches remain in place for a large portion of Minnesota. Over northwest Wisconsin, water content increases, with amounts between 6 and 8 inches. The soil had been rather dry going into winter, but with a shallow frost depth and the fact that at least some of that rain and snow melt may have infiltrated the soil through the past month, the ground may be wet enough that more runoff could occur.

All of that water will eventually become able to run into the river and drainage systems. And our concern for significant flooding really revolves around just how that melt will occur, and what effect any future precipitation will have. This points to an enhanced possibility for minor to moderate flooding. And as water from the tributaries concentrate into the larger rivers, there is a potential flooding could reach major levels.

– NCRFC Spring Hydrologic Outlook: Updated March 22nd, 2023

According to the agency’s models, there’s now at least an 80 percent chance of major flooding at Stillwater — when the river reaches 689′ above sea level.

In response, the Stillwater city council formally announced a state of emergency for the river city on Tuesday, March 21.

“As preparations are underway, this declaration will allow us to move swiftly, taking necessary precautions to mitigate the impact to the community,” police chief Brian Mueller wrote in a memo requesting the resolution.

Starting on Wednesday this week, trails and parking lots along the river in and near Lowell Park are closed to facilitate dike construction. On Monday, March 27, segments of Nelson, Myrtle, and Mulberry Streets east of Main Street will be closed. The city is making its parking ramp at 200 Second Street North free until further notice.

Meanwhile, some volunteers have already begun filling sandbags, through an effort organized by nonprofit Community Thread. After announcing the first opportunities this week, all shifts were quickly filled. The organization says to stay tuned for more opportunities.

Stillwater mayor Ted Kozlowski told MPR News the city is ready to rally behind flood control efforts. But he also said that, at the river levels predicted, downstream communities like Afton and Bayport will also likely be affected.