MidAmerican said it remains in compliance with federal and state laws and that the Iowa Department of Natural Resources, which enforces environmental regulations, has not pursued enforcement at its plants.
MidAmerican, Iowa's largest energy company is owned by Warren Buffett's Omaha, Neb.-based Berkshire Hathaway conglomerate. It serves 732,000 electric customers and 714,000 natural gas customers in Iowa, Illinois, Nebraska and South Dakota.
The Sierra Club declared victory with the settlement.
"Today's settlement marks an important national milestone to end the scourge of coal, as well as an important milestone in our ongoing discussion with Warren Buffett family of companies about combating climate disruption," said Bruce Nilles, senior director of the Sierra Club's Beyond Coal campaign.
MidAmerican defended its environmental record, and says about 31 percent of its generating capacity is now powered by wind.
As part of the agreement, the company will install solar panels at the Iowa State Fairgrounds and an educational display that details tax credits and other information. MidAmerican also will pay $35,000 in attorney fees.