MINNEAPOLIS (WCCO) — The U.S. Army Corps. of Engineers will officially close the navigation system on the upper Mississippi River Dec. 3, after what’s been a bit of an unusual season.

Patrick Moes, with the Corp, says they had to deal with some extremes.

“It’s one of the first times in recent memory that the locks were actually closed twice due to high water, ironically now that we are in severe drought conditions,” Moes said.

But the drought that’s affecting the river down south, is not having an impact on the navigational closing time.

“The closure here doesn’t have anything to do with the drought conditions that are impacting navigation south of St. Louis,” he said. “Traditionally, we close right around this time every year.”

Moes says while the river has not yet frozen over, the Corps will begin winter renovation and maintenance at Lock and Dam No. 6 near Trempealeau County Wisconsin.