The millions of mayflies that lit up the La Crosse, Wisc., weather radar on July 20 are a sign that the water of the Mississippi River is markedly cleaner than just a few decades ago.
Jack Williams, Washington Post: Local
Tue, 07/29/2014 - 10:48am
The millions of mayflies that lit up the La Crosse, Wisc., weather radar on July 20 are a sign that the water of the Mississippi River is markedly cleaner than just a few decades ago.