Legionella bacteria has been found in Riverside High School in Yonkers, officials say.

The school is the first facility in Westchester County to test positive for the bacteria that causes Legionnaires' disease. The potentially deadly disease is often a lethal form of pneumonia.

Department of Public Works Commissioner Tom Meier says the school's cooling towers were cleaned and disinfected right away, before Gov. Andrew Cuomo implemented new rules that require regular testing for legionella bacteria.

"We are way ahead of the curve," Meier says. "We are lucky that the governor instructed us to do this at the beginning of August."

Yonkers officials say Riverside has been cleaned and will be ready for the start of the school year.

Cooling towers in the South Bronx are believed to be the source of the largest outbreak of Legionnaires' in New York City history, killing 12 people and sickening more than 100.

There are seven facilities in Yonkers that contain cooling towers and are owned by the city. In addition to Riverside, there are two other schools, and both of them tested clean. Among the seven facilities is the Hudson River Museum. Officials say all seven sites will be tested and cleaned by Monday.

Legionnaires' disease is a potentially deadly form of pneumonia often found in water systems. Health officials say Legionnaires' is not contagious, nor is it an airborne disease. It is contracted by breathing in a mist or vapor containing the bacteria.

There are currently no reported cases of Legionnaires' in the city of Yonkers.