Stillwater and neighboring cities braced for minor flooding Friday as rain splashed onto the ice-capped St. Croix River and water began backing up from ice jams farther downstream.

The river is expected to rise 7.7 feet by next Friday. Rain is expected intermittently through Monday night, followed by dry days and temperatures climbing to the mid-50s by Friday.

According to Weather Service data, the St. Croix has only a small chance of major flooding this spring. However, the river's level will rise sharply next week and cities along the St. Croix are watching to see what happens after that.

Stillwater has 24,000 new sandbags to fill if water starts approaching downtown, said Shawn Sanders, the city's public works director. City workers and military volunteers from Fort Snelling are prepared to throw up a line of defense if the water rises faster than expected. "We're ready," Sanders said.

Stillwater's last major flooding occurred in 2001, when the St. Croix rose to 692 feet above sea level. Water filled basements at some downtown businesses and swamped the deck of the Lift Bridge, closing it to traffic.

The latest National Weather Service predictions show about a 35 percent chance that flooding could close the bridge again, but that means the river would have to rise 17 feet above Friday's levels.

"Personally I don't think it would happen," Sanders said. "It just depends what the precipitation brings and where the runoff is going."

Any decision to close the Lift Bridge is up to the Minnesota Department of Transportation because a state highway crosses it, he said. About 16,000 vehicles cross the bridge daily.

Afton and Bayport braced

A few miles downstream, Bayport is making its annual preparations, although public works supervisor Mel Horak said it's too early to worry. The southeast corner of Bayport floods every few years, he said, and for many residents who live close to the water, spring flooding has been a way of life. "If you've grown up on the river or gone through a flood, it's all relative," he said.

Afton is bracing for flooding in Old Village, the downtown area, said Mayor Pat Snyder. Flood potential from snowmelt is "particularly troublesome" there, she said, because water collects inside the levee that was built to keep the St. Croix at bay. "All in all, I feel we are well prepared," she said.

Bayport is prepared to fill sandbags, but the bigger cost to the city is the cleanup that follows floods, Horak said.

In Stillwater, moderate flooding will occur if the St. Croix rises to about 687 feet, about 12 feet above the river's normal level, Sanders said. The city wants to build a $7.5 million floodwall that would protect downtown businesses, but money has fallen short.

The river's highest level exceeded 694 feet in 1965, the year of a record flood.

Kevin Giles • 612-673-4432