TRENTON (CBSNewYork) – Thirty Newark Public Schools have been ordered to use alternate water supplies due to elevated lead levels.

The Department of Environmental Protection said it found elevated lead levels at various taps in recent tests. CBS2’s Meg Baker reported officials first realized there was an issue at Louise A. Spencer Elementary School last Thursday where there were reports of discolored water.

“How long ago was this report done? How long did Newark Public Schools sit on this information?” community advocate Donna Jackson asked.

Christopher Cerf, superintendent of Newark Public Schools, told CBS2 he was first briefed on the issue on Monday. However, parents were not notified until Wednesday afternoon.

“Well, we needed to put a plan in place… By the way, we received assurance this was not high-level emergency nature that a day would make,” Cerf said.

Parents were alarmed by the delay.

“I was not aware. I didn’t know until you told me,” Sabrina Olivier told CBS2’s Meg Baker. “The children do need water to stay hydrated during the day. That’s very alarming. As a parent, not knowing, that’s even more alarming.”

The Newark Public Schools system is supplying the schools with alternate water for drinking and for food preparation.

Do not drink water signs on fountains at #Newark Vocational Replaced with water jugs @CBSNewYork pic.twitter.com/28m9bV9SoF — Meg Baker (@megbakertv) March 9, 2016

WCBS 880’s Kelly Waldron reported residents are being asked to drop off cases of bottled water at their local recreational centers.

All drinking fountains at the impacted schools have been shut down. Notices have been put up in bathrooms telling students not to drink water from the taps.

“In 30 schools, no more than four of 10 points were showing elevated lead levels,” Newark Schools Superintendent Christopher Cerf told WCBS 880.

Water points of entry and taps at all public schools – including charters – will be tested.

“I understand in the Flint environment that any sign of elevation is going to make everyone go haywire,” said Mayor Ras Baraka. “But here, the water system in Newark is still safe, it’s still drinkable. There have been some high detectable levels of lead in about 30 of the schools.”

Baraka said the lead is coming from within each school, not from the public works water source.

Sen. Cory Booker, D-N.J., told CBS2 in a statement that he is “deeply concerned” about the elevated lead results.

“Lead in our drinking water is a national issue that requires a robust response from every level of government. Under no circumstance should the health and safety of our children be jeopardized, particularly when they are supposed to be in the confines of a safe learning environment. My staff and I will continue to monitor this situation closely and offer any and all assistance we can to help remedy this problem,” Booker said.

The DEP says no lead has been found in the Newark Water Department’s source water. Lead found in drinking water often due to leaching from lead pipes, household fixtures that contain lead, or lead solder, the DEP said.

“A lot of these are older schools with older piping, with lead piping, or solder, that we need to address long-term,” Bob Constantine of the DEP said.

Concerned parents can have their children take a blood test for lead at the Newark Health Department.

Officials have also begun sending out robocalls to alert parents to the matter.

You can check results of water samples at public schools by clicking here. For additional information about lead in the water, click here. For facts about health impacts of lead in water, click here. Click here for complete results of recent water testing (.pdf).