Image description: These two satellite images show the Mississippi River in August of both 2011 and 2012 in order to illustrate the huge reduction in water levels over the last year.

In August 2011, the river had returned to near normal levels after historic flooding months before. However, the August 2012 image features a much narrower river and new or expanded sandbars. Record-setting temperatures and dry weather have reduced the river from a superhighway to a small road.

The U.S. Army Corp of Engineers maintains a 9-foot shipping channel in the lower Mississippi and has dredges working around the clock to keep the channel clear. Not only are water levels low in 2012, but the floods of 2011 dropped a layer of sediment on the riverbed, reshaping previously open channels.

The Mississippi River has reached record-low levels in some places. The reduced river flow in 2012 has translated into millions of dollars in extra shipping costs, as the loss of just one inch of draft means that a barge can carry 17 tons less than it otherwise would. The result is decreased shipping capacity.

Reduced water levels have had one positive impact: The U.S. Army Corp of Engineers has been able to access and repair levees that were damaged in last year’s floods. The levees are the tan lines that surround the river in these images.

The images were captured by NASA’s Landsat 5 and 7 satellites and are courtesy of NASA.