Why We Need Them
Waterborne parasites sicken some 900,000 Americans every year, and public reservoirs are highly vulnerable to terrorist attack.
How They Work
Slight impurities drive big changes in bluegills´ vitals. Sensors in the tank monitor the fish and sound an alarm when things get out of whack.
The fish stand guard at reservoirs in New York, California and Maryland, where they´ve detected pesticides and a diesel spill.
Bluegills respond indiscriminately to a broad range of contaminants, so technicians must follow up with other tests to pinpoint specific hazards