WEST LAFAYETTE -- The Wabash River occupies a comfortable position in Indiana consciousness. The state designated the waterway as its official river in 1996, and marching bands and a cappella groups pay it homage before Purdue football games and the Little 500 bicycle race. But until earlier this year, no one knew exactly how much the state depended on the river.
Picture a single droplet of water, cruising along the Eels River in Logansport. Suddenly, it’s sucked into a water intake. Within a few seconds it’s loop-the-looping through a tube, cooling down steam generated by the city’s power plant. In less than a minute, it’s out through another tunnel, and back into the river.
Ed Smith, maintenance supervisor at the Logansport Municipal Utilities Power Plant, a coal-fired plant in Cass County and one of the last municipal power plants in the state, explains how the plant uses water from the Wabash River basin to condense the steam that turns its generators, turning it back into water, so it can be heated and turned into steam again.
"It goes in the bottom comes out the top,” he explains, pointing at one of the plant’s two truck-sized condensers, “and then goes out that line and goes right back out to the river.”
It also goes really fast—“as fast as the river flows,” Smith says.
Logansport’s water intake is really small. It uses about 800 gallons per second. That’s about the size of one of those big aquariums you might see in hospital waiting rooms.
Now try to imagine how many aquariums it would take to fill the Wabash River Basin. It’s hard to imagine how all the water in the river could be sucked up, but a new study says there are times Indiana comes dangerously close.
“There’s an environmental engineering myth, or urban legend out there about how much the water in the Mississippi is used and by the time it goes by New Orleans,” Larry Nies, Purdue Professor of Civil Engineering, says.
There’s this chestnut people repeat about how before the water in the Mississippi reaches the Gulf of Mexico, it’s been through a human-engineered system 11 times. Engineers hear this all the time, so Nies and his colleagues tried to quantify it and…crickets. “There’s no information out there,” he says.
They couldn’t confirm it. But they knew someone who might be able to: Julia Weiner, a Purdue student who’s working on her PhD.
The thing is, the Mississippi is really big, so she needed to start smaller -- with the Wabash.
Wiener, along with Nies and professor Chad Jafvert, found that in its more than 475-mile journey, during lower-flow months from July to October, every water droplet goes through at least one human-engineered system, like that power plant in Logansport.
In fact, Wiener says power plants account for about 80 percent of human systems that use Wabash River water.
“It’s very important to acknowledge how much we do already use the water systems,” she says, “before thinking how else we can do with them.”
Wiener says most of the water in these human systems goes right back into the river. But downriver, sometimes it’s used up again. This is something civil engineers call “unplanned indirect water reuse.”
The problem isn’t the fact the water is being used – it’s that not everyone puts it back. When farmers, for instance, use it for irrigation, without putting it back, Wiener says that could spell trouble.
"All the rivers and the streams need a minimum flow to function well,” she explains. “If they don’t, you’re putting at risk the fish, the other animals, and the plants that are related with the river.”
She found that during the summer months, water flows into the river at 165 cubic meters per second, and people are withdrawing about 162 meters per second. That’s only about one Logansport Municipal Utilities worth of difference.
That number’s important to be aware of, because there could be limits to new activities that take water out of the river system, like another power plant.
So far, Indiana’s been lucky. Its river level is relatively stable. Indiana has seen both low-flow periods along the Wabash this year, but it also saw flooding this summer.
So the Hoosier State usually gets plenty of rain. But Wiener’s research might teach engineers and climatologists something about a place like drought-stricken California.
“The principles that are presented there really hold true out here in a lot of California basins as well,” Eric Reichard, the Center Director for the USGS California Water Science Center says. When water’s in short supply, like it is now in California, during the drought, even more human systems might touch a droplet of water than in Indiana.
“The water in our rivers tends to be reused even multiple times,” he says.
And about that question Wiener and her team started with…about the Mississippi River? Based on her study, she estimates the number of times that water droplet from Logansport goes through a system on its way to the Gulf is more like three, not 11. Not so bad for a little droplet from Logansport.