Rising water levels can flood a nuclear plant's pumps, which are part of the system that keeps its reactors at a safe temperature.

Nuclear power plants are required by the federal government to follow security protocols if natural hazards, like flooding, put the facility in danger. According to the Nuclear Regulatory Commission (NRC), Lake Ontario was only a foot short of placing Nine Mile in the lowest-level emergency action plan.

Despite the close call, the plant's owner Exelon did not feel the situation warranted the unusual event status because the high water levels were not threatening operations. So the company appealed for a change.

The proposed amendment was approved. The new lowest-level emergency action plan will be triggered if there is a flooding around the plant that would prohibit plant staff from accessing the site in their vehicles. It will also apply to Exelon's other nuclear plant in Oswego County, Fitzpatrick.

"We want these emergency action levels to reflect actual emergencies as opposed to a condition that was not foreseen when they were developing these levels," said NRC spokesperson Neil Sheehan.