An environmental group has sued Newark over lead in its drinking water.

The lawsuit filed Tuesday by the Natural Resources Defense Council alleges the city has violated safe drinking water laws by not adequately monitoring and testing a water system containing what it calls "dangerously high" lead levels.

In an earlier filing, the group cited a federal report that said Newark's lead levels are among the highest in the country over the last three years for systems serving over 50,000 people.

In a statement Tuesday, the city called the allegations "outrageously false" and said it has complied with state and federal rules to address violations. 

The head of Newark’s water and sewer department is defending the city. Andrea Hall Adebowale says that Newark’s water is perfectly safe to drink.

“We think [the lawsuit] has no credibility. The city has been very transparent about this issue all along,” she says.

Adebowale says that the lead found in residents' homes or in schools comes from pipes and private service lines and not from the city's water system. She say that the city is now in the process of replacing these lead service lines.

“We have identified about 15,000 to 18,000 homes that have lead services lines. Yes, that’s a large number. I’m not trying to say it isn’t. But we feel like it’s manageable,” she says.

The replacement project is expected to cost about $60 million and should take about eight years to complete.

Residents eligible for replacement pipes were mailed letters, but Adebowale says that response from residents has been low. She says that the city wants to hear from these residents.

More information about the replacement program can be found on the city’s website.