Over the years, coal ash has built up along the banks of the Middle Fork River, near Danville.
The chemicals are getting into the water because the coal ash pits weren’t properly cared for when the plant was open.
It closed in 2011 and the pits were never moved.
Environmental groups say it’s been seeping into the water for years.
People say they hope this is the wake-up call the company needs to fix it.
Andrew Rehn, with the Prairie Rivers Network, has been keeping an eye on the problem for the last several years.
"We notified Dynegy.
We intend to sue them under the Clean Water Act if they don’t stop that pollution."
Also they have plans to restore an additional 2500 feet of river bank once they get a permit.
"If there are any chemical pollutants in the water, these activities could be curtailed."