In this four-part public radio special report Bill investigates the origins of the Champaign-Urbana Water supply. He looks at where our water comes from, how much water we have in the ground, how we should best manage that water supply, and how much water we use every day - including water we import from China!
In this first episode Bill introduces the listener to the Mahomet Aquifer by explaining how it was formed. It includes audio clips from David Larson, geologist at the Illinois State Geological Survey and Derek Winstanely of the Illinois State Water Survey. It opens with Bill in his front yard looking for the water cutoff value to his house, then quickly moves to the best geographical point to detect the existance of the undeground Mahmet Aquifer valley. David Larson explains what an aquifer does. Bill closes with a teaser from Winstanley that the water supply isn't infinite.
Bill I suppose like most of us I take for granted the water that comes to my house, until of course something dire happens. [small pause] That metal detector searches for the water cutoff in my front yard as water fills my basement.
Eddie The whole top of the value snapped out; we're lucky the whole value didn't come off the top.
Bill That's Eddie, my plumber, describing the state of the aging water main inside my house. Shaken by the image of water pouring into my basement, I'm no longer complacent about the source of water in Champaign-Urbana [small pause] I start about 30 miles west of my home in Urbana in the small town of Le Roy where I hope to see something invisible to the untrained eye, yet critically important to everyone in this community.
Bill I arrive at the crossroads of Leroy-Lexington Road and McLean County Road 900 North. [pause] Because of my GPS I know I'm exactly 3669.81 miles from Lake Tana in Ethiopia. That's the source of the Nile that created the fertile crescent that gave rise to the Egyptian Empire. Now I'm viewing my own community's Nile if you will. I'm surrounded by miles of flat farm land except If I look due south down Lexington Road the road dips deeply - an unusual feature in the flat heartland of Illinois. To explain what I see here's geologist David Larson from the Illinois State Geological Survey.
Larson "Well, I think the most characteristic thing to observe would be a very broad, long depression in the ground surface, but its miles wide. Its to the point where to the untrained observed they would say 'oh That's nice.' What they are not looking for is the innate third dimension and the time dimension what happened here.
Bill So what happened here? [pause] Buried hundreds feet of beneath me lies the ancient Mahomet Bedrock Valley. Over one million years ago a mighty river cut through the shale bedrock below. With chiseled banks as high as 150 feet it rivaled today's Mississippi River. Starting near the Indiana-Illinois border this majestic river made a graceful u-shape across the region sweeping southwest toward Champaign-Urbana, then turning northwest to Bloomington. The river slowly died when a melting glacier filled it with sand and gravel -- debris that now makes the land where we now work, and play and live. Paradoxically the sand and gravel that killed the river created an aquifer that supplies the water that sustains our lives. Geologist David Larson explains how the Mahomet Aquifer works.
Larson "Actually An aquifer just sits there because the aquifer is the material. So if you think of the sponge analogy - the aquifer is the plastic or that plasticized rubber that makes up the sponge. In the pore spaces between the sand and the gravel, those pore spaces are where the ground water resides. So,he groundwater is the important thing, an aquifer is kinda like the bowl the container."
Bill Trapped in those spaces is the water we use every day to make coffee, wash our laundry, take a bath, and flush our toilets. But how much water can we squeeze from the Mahomet Aquifer? Here's Derek Winstanley, Head of the Illinois State Water Survey.
Winstanley "Its not infinite you can't just withdraw infinities amount of water, otherwise you would suck the whole system dry."
Bill So, tomorrow I look into this question: How much water is there for us to use? And when, if ever, will it run out?