HARRISBURG — One of the most active companies in the state’s natural gas drilling boom was fined more than $1 million on Tuesday, including a penalty that state officials called the single largest fine for an oil or gas operator in the state.

The state Department of Environmental Protection said the action stems from Chesapeake Energy Corp.’s contamination of private water supplies with methane in northern Pennsylvania’s Bradford County and a February tank fire at a drilling site in southwestern Pennsylvania’s Washington County.

“It is important to me and to this administration that natural gas drillers are stewards of the environment, take very seriously their responsibilities to comply with our regulations, and that their actions do not risk public health and safety or the environment,” DEP Secretary Michael Krancer said in a statement.

Chesapeake will pay $900,000 in the gas migration case and $188,000 for the tank fire.