A coal ash spill in Tennesee late last year unleashed a billion gallon tsumani of toxic sludge. There are atleast 1300 of these coal ash ponds in the USA and as the New York Times notes:
…most of these dumps, which reach up to 1,500 acres, contain heavy metals like arsenic, lead, mercury and selenium, which are considered by theEnvironmental Protection Agency to be a threat to water supplies and human health. Yet they are not subject to any federal regulation, which experts say could have prevented the spill, and there is little monitoring of their effects on the surrounding environment.
Indiana ranks 1st in storage of toxic sludge– mostly along southern Indiana rivers.