Amargosa Valley, Nevada
From the sign (leftmost photo below):
"Crystal Spring once fed a small but important stream that was home to a variety of wildlife. Species such as the Ash Meadows pupfish and ???? relied on the constant source of water -- a ?? necessity in the desert habitat.
"But in the 1960s a concrete ditch was built to divert Crystal Spring to water crops. The plants and animals that once lived in the stream disappeared. In 1997, refuge staff and partners diverted water back into the original stream bed. The winding channel slowed the water so algae and other plans could grow.
"Today, thanks to these changes, the stream once again abounds with life. Ash Meadows Pupfish eat the algae. Toads lay their eggs in the pools. Birds, such as Marsh Wrens and Song Sparrows and mice find shelter in streamside vegetation. Hawks and coyotes prey on these small animals. People, too, are drawn to this beautiful place, and the opportunity to watch a greater variety of wildlife.
For more info:
http://www.r1.fws.gov/desert/ash-noframe.htm