After an especially severe flood in 1950, the US Army Corps Of Engineers designed a diversion channel to carry flood water past the populated areas in Aitkin County. The river makes a large U-shape, with the City of Aitkin at the bottom of the U. The Corps of Engineers dug a channel across the top of the U. The diversion channel is 6-1/4 miles long, but it cuts off 24 miles of river. It works because water always wants to flow down the steeper path. The shorter the path, the steeper it will be.
To prevent all the Mississippi River from using the diversion channel, a low head dam was installed at the entrance to the channel. During low and normal river levels, all water flows down the river channel past Aitkin. Once water rises to the level of the dam, it starts to flow over the dam and into the diversion channel. That serves to limit the maximum flow going down the river channel, and diverts flood water into the diversion channel. It is a totally passive system working on gravity alone.
In 50 years of operation, it is estimated that the Aitkin Diversion Channel has prevented $22-million in flood related damages. The top two photos are look east from the western most of two bridges that cross the channel. One photo is a wide-angle, the other a telephoto shot. The bottom photo is looking east from the eastern most bridge. The channel makes a slight curve to the right in the distance. The low head dam and the Mississippi River main channel are just around that curve.
