The details have been posted in several earlier threads, but the TL;DR version is: 1) Detroit was gouging Flint, well into 7 figures per year, (plus the supply

The details have been posted in several earlier threads, but the TL;DR version is: 1) Detroit was gouging Flint, well into 7 figures per year, (plus the supply pipes from Detroit to Flint have lead) 2) Flint signed a new deal for a new supply direct from Lake Huron with lead-free supply lines at an 8-figure cost savings per decade (or less) -- better water, much cheaper. Construction to take ~4 years. 3) Detroit hears this, cuts off Flint at earliest opportunity (1-year notice opt-out), apparently assuming that they could later gouge even more under the assumption that Flint had no alternative; 4) Flint resorts to using Flint River in the interim (until new Huron feeds from new water system are complete), prepared for the bacterial risks but unaware of lead risks.