The Environmental Protection Agency is failing its congressionally-mandated mission to monitor the nation's water supply, a new lawsuit by a trio of environmental groups allege in a new federal lawsuit filed Wednesday.

The Waterkeeper Alliance's filing in the U.S. District Court for the Southern District of New York claims the agency has shirked responsibilities placed on it by updated federal legislation in 1996 to identify and seek to regulate contaminants in the water supply.

As the complaint notes, while approximately 90 drinking water contaminants are presently regulated under national primary drinking water regulation, since the most recent updates to federal law were passed 23 years ago, the agency's mandated processes for reviewing, recommending and updating its list of contaminants to regulate has led to the revision of only one existing regulation. Not one new chemical has come under regulation since 2000, the complaint claims.

The suit says the EPA, since President Donald Trump took office, has actually reversed progress on regulatory efforts.

In May 2018, under its regulatory power, the EPA announced it was initiating steps to evaluate the need for regulations on per- and polyfluoroalkyl substances. The chemicals are used to resist grease, water and oil in such things as nonstick cookware coating, water-repellent clothing, and some cosmetics, according to federal officials. The substance has been linked to polluted tap water in a number of communities, including in Hoosick Falls, New York, according to the complaint.

However, earlier this month, EPA Acting Administrator Andrew Wheeler reportedly signed off on a decision not to regulate the chemicals under the federal Safe Drinking Water Act.

“In contrast to the extensive delays in EPA's regulation of drinking water contaminants, the agency acted expeditiously in deciding not to regulate these highly toxic and widespread contaminants under the Act,” the complaint states.

“At the same time the Trump administration is proposing to weaken the Clean Water Act and is actively allowing toxic chemicals to pollute our drinking water, it also is failing to comply with the Safe Drinking Water Act, which stops polluted water from reaching our taps,” Waterkeeper Alliance Executive Director Marc Yaggi said in a statement. “EPA is supposed to protect human health and the environment, but its actions and omissions are threatening one precious resource we all need: clean drinking water.”

The 1996 update to federal law required the EPA to conduct a series of actions every five years to identify unregulated chemicals in the water supply, list new candidates for regulations and determine whether at least five unregulated contaminants should be regulated. Every six years, the agency is supposed to review and revise the national primary drinking water regulations when appropriate.

The suit alleges the EPA has not “timely” complied with its mandate and “has not safeguarded public drinking water as Congress intended.” As such, the complaint seeks to have the court force the agency to complete the review or revise its regulations on a host of contaminants, including chromium.

A spokeswoman for the EPA said the agency does not comment on pending litigation.

The Waterkeeper Alliance is joined in the suit by its affiliates, Waterkeepers Chesapeake and the California Coastkeeper Alliance. The plaintiffs are represented by private attorney Reed Super.