Search continues for boater after pontoon found floating in Mississippi River between Minnesota, Wisconsin

Authorities are searching for a missing man after his pontoon was discovered unattended in the Mississippi River between Minnesota and Wisconsin on Thursday.

The Buffalo County Sheriff's Office in Alma, Wisconsin, says Brian Daley's boat was found "tied off along an island" by Merrick State Park near Fountain City.

On Friday, the sheriff's office said someone reported finding Daley's boat "floating unattended" in the river's main channel. That person then tied it off near the state park, the sheriff says. 

Several agencies, including the Winona County Sheriff's Office in Minnesota, are still searching for Daley, focusing on a span between Merrick State Park and Bass Camp Resort across the river near Whitman, Minnesota.

The sheriff's office says Thursday's aerial and ground searches transitioned to an "underwater" search on Friday.

"At this time, the Buffalo County Sheriff's Office and Winona County Sheriff's Office are not requesting volunteers or members of the public to participate in physical search operations," authorities said.

Anyone with information on this case is asked to call the Buffalo County Sheriff's Office at 608-685-4433, or the Winona County Sheriff's Office at 507-457-6368.