Dan Corkery: At least we're talking about the Mahomet Aquifer


Dan Corkery: At least we're talking about the Mahomet Aquifer

Try this little social experiment: Say "Mahomet Aquifer" to a friend and see if the conversation moves to "PCBs."

Or try it in reverse: Just say "PCBs." I bet your friend will say something about protecting the Mahomet Aquifer, the only source of drinking water for Champaign-Urbana and other communities in central Illinois.

Here's what you probably will not hear:

If any toxins were ever to leak into the aquifer from the Clinton landfill (where owners are seeking the bury polychlorinated biphenyls), no one in Champaign County would be drinking that poisoned water.

It's true, contrary to some of the fears expressed locally that these persistent carcinogens might work their way into our water.

The Mahomet Aquifer, which lies about 200 feet underneath us, is a vast reservoir of water-saturated sand and gravel, nestled in a the valley of ancient river bed. That valley slopes from east to west. Generally speaking, the water flows slowly westward to the Illinois River.

The Clinton landfill in DeWitt County, about 35 miles to the west of the twin cities, is downstream.

Could C-U's water usage draw water that far upstream?

"Theoretically, it could happen," said Derek Winstanley, retired chief of the Illinois State Water Survey. "But ... extremely unlikely."

But Champaign-Urbana does manage to pull some of the aquifer's water upstream. Just west and north of Champaign, wells are pumping out enough water that we have created a "cone of depression" within the aquifer, that extends about 20 miles outward. This depression manifests itself as lower water pressure. According to Winstanley, well levels have fallen about 80 feet in the 180 years since this area has been settled.

Are we pumping our aquifer dry?

Not so far. A report by the Water Survey in December 2011 concluded "none of the current groundwater users in the Mahomet Aquifer could be considered 'at risk' for a future water shortage."

But who knows what the future holds?

Because of that unknown, Winstanley and others want the community talking about the aquifer. "What this Clinton landfill issue has done is generate a lot of public concern about the possibility of contaminating the aquifer," Winstanley said. "So even though the focus is just on Clinton, that focus should be extended to the rest of the aquifer."

For Winstanley, Champaign County should be discussing what measures need to be put in place to guarantee a sustainable, safe water supply.

"Champaign County is the bulls eye, the big cone of depression," Winstanley said. "If we're going to do something, this is the place to do it."

He and others — including Brad Uken of the Champaign County Farm Bureau and Cameron Moore of the Champaign County Regional Planning Commission — have been trying to form a local coalition that would, among other things, recommend how our local water resources ought to be managed.

That effort, Uken said, has been put on hold. The hope is, the group will restart its work later this year.

One of the key questions for local planners is, where is the aquifer being recharged? Just like a bank account, if nothing is coming in, withdrawals will eventually empty the thing.

There's evidence that in northern Champaign County, surface water is helping to recharge the aquifer.

If those locations can be identified, for example, planners could keep large developments from being built there, so as not to shut off the aquifer's recharge spigot.

Dan Corkery is a member of The News-Gazette's editorial board. He can be reached at 217-351-5218 or dcorkery@news-gazette.com.