From The New York Times:
The scope of cyberattacks on U.S. water systems has grown to include at least seven states and may be far wider, officials and experts warned, as the authorities raced to safeguard the nation’s water supply against an assault that increasingly appeared to be the work of Iran. While there were no indications that any water supply had been altered or made unsafe to drink, state and local officials throughout the country were on high alert for potential problems in vulnerable computers that are commonly used to monitor and adjust water quality, including chemical-treatment levels and water pressure. Minnesota first publicly reported the attacks, and now Michigan says its systems have also been targeted.
The attack has little precedent, experts said, but has long been the stuff of nightmares and sensationalized Hollywood thrillers: an apparent cyberattack by a foreign power during a time of war that could, at least in theory, jeopardize the health and safety of Americans.