A USA Today investigation finds that "More often than once a week, the physical and computerized security mechanisms intended to protect Americans from widespread power outages are affected by attacks, with less severe cyberattacks happening even more often."
"Between 2011 and 2014, electric utilities reported 362 physical and cyberattacks that caused outages or other power disturbances to the U.S. Department of Energy. Of those, 14 were cyberattacks and the rest were physical in nature... Often, such incidents are shrugged off by the local police who initially investigate."
"While the Department of Energy received only 14 reports of cyberattacks from utilities over the past four years, other reporting systems show rising cyberthreats. The branch of the Department of Homeland Security that monitors cyberthreats received reports of 151 'cyber incidents' related to the energy industry in 2013—up from 111 in 2012 and 31 in 2011. It is uncertain whether the increase is due to more incidents or an increase in reporting."