Chesapeake Energy has revealed that it is cooperating with a grand jury proceeding and an Environmental Protection Agency (EPA) investigation into the company’s Clean Water Act (CWA) compliance at certain sites in West Virginia.

In its annual report the company said it has responded to all pending orders from EPA and is working to resolve problems regarding a compliance action initiated in late 2010. For four of the sites in the EPA action, Chesapeake said it has responded to a subpoena requesting documents from a grand jury of the U.S. District Court for the Northern District of West Virginia.

“We understand that the U.S. Department of Justice (DOJ) is investigating possible criminal violations of and liabilities under the CWA with respect to three of the four sites. We are cooperating with the DOJ’s investigation,” the Chesapeake annual report said, noting that its duration and outcome are uncertain.

The CWA provides varying degrees of penalties for both civil and criminal violations, including criminally negligent conduct or “knowing” conduct. “We believe that resolution of the EPA’s compliance orders and the DOJ’s investigation will each include monetary sanctions exceeding $100,000…”