Water fountains at 30 schools in Newark, New Jersey, were shut off on Wednesday after elevated levels of lead were found during testing, the state Department of Environmental Protection said.

Lead was detected in nearly half of the schools in the Newark Public Schools system, the state's largest, with about 35,000 students. Fountains will remain closed until more testing is conducted, said Lawrence Hajna, a DEP spokesperson.

The school system said other water sources have been brought in for use.

Of the about 300 testing samples taken at 30 school buildings, 59 had lead levels above the federal government's threshold level that requires further action, including testing.

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Newark parents were notified about the incident in letters from the school system and told not be concerned as drinking water alone is not typically associated with elevated blood lead levels. A help phone line was set up for parents with questions.

Lead exposure, which often has no obvious symptoms, can affect nearly every system in the body, according to the Centers for Disease Control and Prevention.

Lead has not been found in the water supply of the city of Newark, home to 280,000 residents, the DEP confirmed. Newark is 11 miles west of New York City.

Awareness over lead in drinking water was raised by the water contamination crisis in Flint, Michigan. Newark is the latest school district to turn off its water supply, following similar actions by schools in Jackson, Mississippi; Ithaca, New York and Binghamton, New York.

On Monday, the DEP said it was notified by the school system that elevated lead levels were detected during annual testing in the district and that it has since requested the system's past test results.