The Oyster Creek nuclear plant in New Jersey was placed on alert on Monday night as Hurricane Sandy sent water rising 6 feet above sea level.
ABC reports that the surging water levels prompted safety officials to declare an "unusual event" around 7 pm on Monday evening, and an "alert" two hours later.
An "alert" is second from the bottom in a four-tier warning system.
The Nuclear Regulatory Commission (NRC) said that a confluence of factors including rising tides, wind direction and Superstorm Sandy pushed water levels up in the plant's intake structure.
The water levels are expected to recede within hours, however, and the plant, which was built in 1969 and is capable of providing power to 600,000 homes a year, is still in a safe condition.
The NRC reports that all other nuclear plants in the region have so far successfully weathered the extreme conditions, and no plants in operation prior to the storm's onset are expected to shut down.
Inspectors had already been deployed to nuclear power stations in the path of Hurricane Sandy over the weekend to monitor conditions. Over a dozen nuclear plants are on Hurricane Sandy's path, and observers have expressed concerns about their age and ability to withstand the extreme weather conditions, as well as the similarity of reactors to those used in Fukushima.