The USGS Water Science School
In the past few years the U.S. Geological Survey has been involved in a nationwide study of the water quality of watersheds throughout the United States. The program is called the National Water Quality Assessment Program. Sixty large drainage basins are being studied to investigate the water quality in the places where most of the U.S. population lives.
The local study in Georgia is the Apalachicola-Chattahoochee-Flint River Basin study. One part of this study was to check the fish in different parts of the basin to see if and how they were affected by local pollution and chemicals, such as pesticides.
The hydrologists had to come up with a way to collect the fish, and this picture shows them in action. They are actually shocking the water with a strong electrical charge to stun the fish into submission so they can be collected. The guy on the left has a power pack on his back and is holding the electrical wand. At the right moment, he submerges the wand in the creek, presses a button, and then... zap 'em and bag 'em.