Boaters, canoeists and kayakers were warned about dangerous high water as the St. Croix River crested this weekend far above its normal levels.

Heavy rain in May pushed the river up at least 7 feet, causing late-season minor flooding, threatening basements of riverside houses and triggering a no-wake rule for boaters from Taylors Falls to Prescott, Wis.

Fed by the swollen Namekagon River in Wisconsin and other overloaded tributaries, the St. Croix swamped dowtown parks in Stillwater and Hudson, Wis. Several boat landings were closed. The National Park Service warned that the St. Croix and Namekagon rivers "are flowing high, fast and cold," and "strongly discouraged" anybody from going onto the river this weekend.

"It's really pulling downstream fast," said Commander Jerry Cusick of the Washington County Sheriff's Office, which puts a patrol boat on the St. Croix on evenings and weekends. "It's not going to be what they normally expect when they come down to the St. Croix. It's fast and it's dangerous down there."

The St. Croix was expected to crest at 682.6 feet above sea level on Sunday, a level that could close the Stillwater Lift Bridge. The river won't recede much until midweek.

Just two months ago, meteorologists declared Minnesota in the jaws of a drought they thought would worsen. Now the river is showing its might.

"If we don't get a lot more rain the peak will start to drop very rapidly," said Molly Shodeen, a Minnesota Department of Natural Resources hydrologist. Possible rain was forecast for Sunday night.

The no-wake rule is essential, she said, because of "tremendous erosion" from waves. "On the St. Croix it isn't the fast water that's really the issue, it's the wakes that grind out that shoreline," Shodeen said.

The difference between high water this weekend and occasional spring floods that happen in March, she said, is that most boats now are back in the water and docks are in place. The river will push "tons of floating logs" downstream, she said.

National Weather Service projections of St. Croix River depths are available at www.startribune.com/a1314. National Park Service advisories are available at www.startribune.com/a1325.

Kevin Giles • 651-925-5037 Twitter: @stribgiles