Worries over bacteria led to the fateful decision not to apply anti-corrosive chemicals when Flint, Michigan, began drawing water from the Flint River, an email written by the city's former public works director says. The failure to deploy corrosion controls after the city switched to the river from the Detroit municipal system in April 2014 has been widely considered a catastrophic mistake that enabled lead to leach from aging pipes and reach some homes. Flint's water supply was switched to save money when the city was under state emergency financial management, an interim measure while a new pipeline to Lake Huron is built. Federal regulators say Michigan officials ignored the EPA's advice to treat Flint water for corrosion-causing elements last year and delayed for months before telling the public about the health risks.