FLINT, MI -- A foreman at the Flint water plant warned his sister that the city was not prepared to treat Flint River water in 2014, telling her, “It’s not safe. We’re not ready. People are gonna die,” according to a new report from the PBS program Frontline.

In a story published online Thursday, Sept. 5, Tonja Petrella, the sister of Matt McFarland, who worked as a foreman at the plant until his death in 2016, told Frontline that her brother called her the day before the city’s water supply was changed to the Flint River in April 2014, warning, “Tonja, contact everyone you know in Flint, anybody you care about, and tell them, do not drink the water.”

Flint’s plant had not regularly treated water that was distributed to homes and businesses for decades, but state-appointed emergency managers made a series of decisions that put the plant into full-time operation in a failed attempt to save money by using the river as no-cost source water.

The story of Petrella and McFarland is part of an episode on the Flint water crisis that Frontline is scheduled to air on PBS stations at 9 p.m. Tuesday, Sept. 10.

McFarland is not the only city employee to have warned that Flint was in no position to safely treat water at the time the plant was put into service, triggering the city’s water crisis.

Experts and government officials have said the improperly treated water was a shock to the Flint water distribution system because of its extreme corrosivity, causing lead to leach from distribution pipes and home plumbing.

Former utilities administrator Michael Glasgow told The Flint Journal-MLive in 2016 that he was following “marching orders” from supervisors when he helped put the plant into service despite his objections.

Just eight days prior to the city’s use of the Flint River, Glasgow warned state regulators of a potential disaster on the horizon in an email on April 17, 2014.

“I was reluctant before, but after looking at the monitoring schedule and our current staffing, I do not anticipate giving the OK to begin sending water out anytime soon,” Glasgow’s email says. “If water is distributed from this plant in the next couple weeks, it will be against my direction.”

McFarland, 43, was found dead April 16, 2016, by a friend in his Otter Lake home, according to Flint Journal files.

His death drew international attention from major media outlets and conspiracy theorists alike, some of whom suggested his death was part of a government cover-up of how the water crisis unfolded -- an attempt to silence witnesses in an investigation that led to criminal charges against 15 city and state workers.

Former Michigan Attorney General Bill Schuette’s office confirmed after his death that McFarland was previously interviewed as part of its investigation into the city’s water crisis.

Lapeer County police said there were no signs of foul play at the time of his death.

Despite criminal charges related to the water crisis having been filed, and seven of those cases resulting in plea agreements, prosecutors from the attorney general’s office dismissed eight pending criminal cases related to Flint water in June, saying they were built on weak foundations and were filed without a full investigation of all available documents and evidence.

Solicitor General Fadwa Hammoud has said her criminal investigation of Flint water is ongoing and the charges were dismissed without prejudice, meaning they could be filed again.