All three Twin Cities locks on the Mississippi River were closed to commercial boat traffic Thursday morning because of high, fast-moving water.

The locks include Lock and Dam No. 1 near the former Ford plant in St. Paul, and the Upper and Lower St. Anthony Falls locks in downtown Minneapolis near the Stone Arch Bridge. The locks were closed to recreational boats last weekend.

The U.S. Army Corps of Engineers, which operates the river's lock and dam system, is required to close them to commercial boat traffic when flows reach 40,000 cubic feet per second (cfs), said George Stringham, corps spokesman. The standard for recreational boats is 30,000 cfs.

Stringham said that depending on the weather, the locks are unlikely to open to commercial boat traffic any sooner than the middle to later part of next week. The locks typically operate a half-dozen times a day, Monday through Saturday, allowing about a dozen or more barges to pass. For recreational boats, it's too far out to predict when it will be safe again, he said.

"It's going to come down slowly," Stringham said of the river level. "It's not like a flash flood, where it jumps up and then jumps right down again. Plus, everything upstream is already saturated."

The strong currents created by high water make it too dangerous for navigation through the locks, and boats burn more fuel fighting the currents, Stringham said.

Meanwhile, the state's raging rivers at the moment are not going to be safe for novice boaters, regardless of the type of craft, said Stan Linnell, boating and water safety manager with the Minnesota Department of Natural Resources (DNR).

"River levels are very high right now," he said. "It's not for the inexperienced paddler — and it's not for the inexperienced boater, for that matter."

Dealing with currents, unexpected debris swept into the water and other hazards created by fast and high water pose a risk for the next week or so — including the July 4th holiday.

"It's probably best to stay off the rivers until they calm down a little bit," he said, adding that a nice lake is the preferred option.

Experienced boaters should take added precautions, like scouting the river, choosing a wider river and verifying river depths and conditions on the DNR's website at www.dnr.state.mn.us/river_levels/index.html.

And in these conditions, he added, it's especially important that boaters wear a properly fitted life jacket.

Jim Anderson • 651-925-5039 Twitter: @StribJAnderson