FLINT, Mich. — Shortly before this poverty-stricken city began drawing its drinking water from the Flint River in April 2014 in a cost-cutting move, officials huddled at the municipal water treatment plant, running through a checklist of final preparations.

Mike Glasgow, the plant’s laboratory supervisor at the time, says he asked district engineer Mike Prysby of the Michigan Department of Environmental Quality how often staffers would need to check the water for proper levels of phosphate, a chemical they intended to add to prevent lead corrosion from the pipes. Prysby’s response, according to Glasgow: “You don’t need to monitor phosphate because you’re not required to add it.”

Recalling the meeting Tuesday in an interview with The Associated Press, Glasgow said he was taken aback by the state regulator’s instruction; treating drinking water with anti-corrosive additives was routine practice. Glasgow said his gaze shifted to a consulting firm engineer in attendance, who also looked surprised.

“Then,” Glasgow said, “we went on to the next question.”

In hindsight, he said, it was a fateful moment. For nearly 18 months, Flint residents would drink water that had coursed through aging pipes and fixtures, scraping away lead from lines that ran from water mains to some homes and schools.

By the time Gov. Rick Snyder announced in October 2015 that Flint would return to the Detroit system, from which it had bought treated Lake Huron water for decades, scientists and doctors had reported dangerously high levels of lead in numerous water samples and a spike in the proportion of children with elevated lead in their blood. Even low amounts of lead are a health threat, especially for young children, as it is linked to lower IQs and behavioral problems.

Flint residents still are advised not to drink unfiltered tap water.

In a report last week, a task force appointed by Snyder to investigate the water crisis described the state as “fundamentally accountable,” partly because of the DEQ’s instruction to omit corrosion controls. It also assigned lesser blame to the state Department of Health and Human Services, local and federal agencies and emergency managers Snyder had appointed to oversee city operations.