In an era of increasingly sophisticated technology, two treatment plants on the Mississippi River are experimenting with what might be the original water-quality gauge: mussels.

Water departments in Minneapolis, Minnesota, and Moline, Illinois, are using native freshwater mussels in pilot programs as early-warning systems to detect possible contamination in the river. The mussels — Actinonaias ligamentina, a small, brown bivalve also known as mucket clams or mucket mussels — clamp their shells shut when they sense contaminants. Researchers believe that reaction could tip off water operators to potential problems with drinking water sources.

“It’s nature telling us that there might be something wrong with the water,” says George Kraynick, water-quality manager at Minneapolis Water Treatment and Distribution Services. “They’re kind of just like people breathing air. If we smell something, we’re going to leave the room or look around for it. These guys close up because it’s not something they want to bring inside them.”

The projects began at several Mississippi River sites with support from a U.S. Environmental Protection Agency grant. That money dried up, but Minneapolis and Moline continued the work on their own with technical support from Joel Allen, an environmental scientist at the EPA in Cincinnati, Ohio.

Each municipality keeps mussels — 11 in Minneapolis, 16 at Moline — in climate-controlled tanks that constantly receive running water from the river via intake stations. That’s critical, as the muckets live by filtering bacteria, protozoans and other organic matter out of the water. A biomonitoring system in the tanks uses magnetic sensors that track the gape between the mussels’ valves (shells) and note when they shut, which might indicate water-quality problems.

Of course, water plant operators already monitor river water for organic material washed into the water by rain or runoff as well as contaminants such as fuel, herbicides, solvents or heavy metals from spills or other accidents. However, a human’s sense of smell isn’t as keen as the mussels’ perception of microcontaminants. Further, the muckets’ reaction provides a warning faster than lab tests.

“That will serve as an alert that we will further investigate,” says Bob Bohannon, water lab chemist with the City of Moline’s Water Division. “We as humans think we’re very sophisticated, but we sometimes can’t tell whether or not the water is good enough to drink. Yet these mussels, which are simple organisms, can detect that.”

Program results have been encouraging, but officials haven’t quite perfected the system. The mussels sometimes close their shells on their own, so researchers must analyze those reactions and water-quality parameters to distinguish normal behavior from a protective reaction. Kraynick said Allen is working on an algorithm to determine when something in the water makes the muckets close, which could lead to definitive evidence of trouble.

The mussels require little maintenance. Kraynick said Minneapolis staffers monitor their clams several times a day and clean the tank with fresh river water about twice a week. Eventually, the muckets will outgrow their sensors and need to be refitted. Bohannon said Moline’s situation differs somewhat, as their mussels are off site about 4 miles away, so workers change the water about every other week.

The mussels at Minneapolis and Moline haven’t alerted officials to any contamination yet. However, Kraynick and Bohannon said that’s not unexpected, as such events are relatively rare. Still, a January 2014 chemical spill in the Elk River of West Virginia, which left up to 300,000 people without potable water for days, illustrated the importance of early-detection mechanisms. A similar event on the Mississippi might prove catastrophic, as the Quad Cities (Davenport and Bettendorf, Iowa, and Moline and East Moline, Illinois) draw drinking water from the river. The Minneapolis facility draws water for eight municipalities.

“With the huge amounts of crude oil coming out of the Dakotas and Canada and all the ethanol being produced in Iowa, the chances of something like that happening in the future are just increasing,” Bohannon says. “These (mussels) serve as a check.”

Kraynick and Bohannon want to continue with the experiment but need to work with partners to determine future funding. Meanwhile, Kraynick says, Allen plans to partner with the EPA and the U.S. Department of Homeland Security on the project.

“The three of us are going to get together to figure out how to get the funding,” he says. “We’re planning on funding some of this on our own because we think it’s a great way to protect our citizens.”

Assuming they find adequate money and determine a specific role for the mussels, Kraynick and Bohannon would love to see the clams serve long term as part of a comprehensive early-warning system.

“You never know where this could lead in the future,” Bohannon says. “I think our efforts are fruitful in promoting the march of science.”