Not true. Water maintenance problems start years before.
I don't remember the details, but at some point Flint changed its water supplier over the protests of the water bureau. Different water -> different chemical composition -> more leaching (wikipedia says it was in 2014).
The change happened with the emergency manager in place and was signed off by the state government. Moreover, the change was TO Detroit water and Detroit was also being run by the state at the time.
I don't remember the details, but at some point Flint changed its water supplier over the protests of the water bureau. Different water -> different chemical composition -> more leaching (wikipedia says it was in 2014).