A Coast Guard response boat now is on the Willamette River searching for a possible boater in trouble.
About 8:27 p.m., Coast Guard Petty Officer Jeremy Burns in Portland said a call of "mayday, mayday, mayday" was picked up on a marine band radio.
Three Multnomah County Sheriff's River Patrol boats responded on the Columbia River and searched the perimeter of Government Island, Burns said. The Interstate 205 Bridge crosses Government Island.
Nothing was discovered and those boats returned.
A Coast Guard 25-foot RBS craft continued the search in the Willamette.
No other information was available.