Biologists say they don't know yet why zebra mussels disappeared from a 25-mile stretch of the St. Croix River. They think either turbulent water or hungry carp might be behind the sudden retreat of the invasive shellfish that displaces native species.

A hiker first reported milky, cream-colored water flowing into the St. Croix late last month. A DNR investigation has traced the water to a sand mine near Grantsburg, where a holding pond had begun leaking. The investigation continues.

The U.S. Senate unanimously authorized construction of a new St. Croix River bridge near Stillwater. The move comes after 15 years of debate over how to improve traffic flow while also protecting the St. Croix, which is a National Scenic River.

Drivers will once again be able to cross the Stillwater Lift Bridge in about a month. The bridge, which connects Minnesota and Wisconsin across the St. Croix River, closed Sept. 10 for the rehabilitation project.

In the mid-century years many Minnesotans were lured across the St. Croix River by big block letters proclaiming the site of the Buckhorn Tavern and supper club. The dining and dancing was ended by a fire that claimed the club more than 50 years ago. Now the sign will finally come down as part of a deal with the landowner to restore the river bluff.

Supporters of a new bridge near Stillwater have been pushing the concept for decades. They believe they can finally reach their goal if the House votes to exempt part of the St. Croix from its status as a Wild and Scenic River. But the bridge has its critics. They're using financial arguments in hopes of rallying opposition.

A dive team Monday night was searching the St. Croix River in Hudson, Wis., for the body of a Lake Elmo 18-year-old who had been trying to swim across the St. Croix channel. The teen made it about a third of the way, began to struggle, turned around to go back to the dike and went under, investigators said.