XTO Energy, Inc., a subsidiary of ExxonMobil, has agreed to pay a civil penalty of $2.3 million for violations of the Clean Water Act at its hydraulic fracturing sites in West Virginia.

The company — the largest holder of natural gas reserves in the United States — will also spend a further $3 million to restore eight sites damaged by unauthorized discharges of sand, dirt, rocks and other fill material into streams and wetlands in connection with its hydraulic fracturing operations, according to the U.S. Environmental Protection Agency (EPA) and the Department of Justice (DOJ).

The federal government and West Virginia Department of Environmental Protection allege that the violations impacted more than 5,300 linear feet of stream and 3.38 acres of wetlands. The Clean Water Act prohibits the filling or damming of wetlands, rivers, streams and other waters without a permit from the U.S. Army Corps of Engineers.

As part of the settlement XTO has also agreed to implement a comprehensive plan to comply with federal and state water protection laws at its West Virginia oil and gas extraction facilities that use horizontal drilling methods.

Commenting on the settlement agreement, Sam Hirsch, acting assistant attorney general for the DOJ's Environment and Natural Resources Division, said: "The extraction of domestic energy resources is vitally important, and so it is equally important that companies ensure that all activities are done in accordance with the nation's environmental laws."

"This settlement will resolve allegations that XTO damaged wetlands and streams by illegally discharging dredge and fill materials into streams, and restore wherever possible these damaged natural resources," Hirsch added.