Also the Gnat Catcher.
A biologist,Dr. David Eitner at the University of Tennessee, found the Snail Darter to only living in the Little Tennessee River and effectively stopped the building of the Tellico Dam...In 1975, the Snail Darter was placed on the Endangered Species List. Construction of the dam was halted for 4 years...Then, the tiny fish was found in several other rivers and streams in East Tennessee and the dam was completed in 1979...