Attackers have been making serious inroads into U.S. government, utility and military networks for most of this decade. Government officials and the operators of the power-generating companies have known about these attacks for some time, but little has been done to stop them or clean up the damage. For a variety of reasons lack of funding, lack of expertise on information security, poor communication with peer companies the organizations that run the electrical grid and other utilities have not been able to put the right defenses in place.
Source: https://threatpost.com/electrical-grid-attacks-have-been-ongoing-years-040909/72506/