In three months the principle reservoir that supplies water to the City of Atlanta will be empty, unless there is a sizeable amount of rain, which looks increasingly unlikely. In spite of these grim forecasts the US Army Corps of Engineers, which controls the reservoir has steadily released more than 10x the amount of water that flows in to the reservoir every month. So why is the Federal government slowly draining the primary source of water for 5 million people. Why you ask? The answer is simple: Mussels.

That’s right the Army Corps of Engineers is mandated to release a continuous flow of water (in the 100s of millions of gallons) in order to maintain the habitat of a species of mussels downstream near Florida's gulf coast.

Apparently these mussels must be protected from the drought, meanwhile 5 million Atlantans will soon be reduced to bathing in and drinking mud…thanks to the federal government for always keeping its priorities in order.
http://www.ajc.com/metro/content/metro/stories/2007/10/10/wateruse_1011.html