Environmental groups have asked the Illinois Environmental Protection Agency to revive coal-ash pollution rulemaking after required federal monitoring data said 22 of 24 ash impoundments at state coal-fired plants have contaminated groundwater with toxic pollutants.

The agency proposed a state coal-ash rule in 2013 after a 2008 massive ash spill at a plant in Kingston, Tenn., but approval remains pending before the Illinois Pollution Control Board. State officials did not respond to a request for comment.