The problem with lead in the drinking water didn't start 50 years ago. The real problems began in the 1980's when GM downsized and Flint's economy started to die. n 2011, the state of Michigan took over Flint's finances after an audit projected a $25 million deficit.
In order to reduce the water fund shortfall, the city announced that a new pipeline would be built to deliver water from Lake Huron to Flint. In 2014, while the pipeline was under construction, the city turned to the Flint River as a water source. Soon after the switch, residents reported changes to the water's color, smell and taste.
Tests in 2015 by the Environmental Protection Agency (EPA) and Virginia Tech indicated dangerous levels of lead in the water at residents' homes.
A class-action lawsuit charged that the state wasn't treating the water with an anti-corrosive agent, in violation of federal law. As a result, the water was eroding the iron water mains, turning the water brown. So no, the problem with lead in the water isn't something that started 50 years ago, it is a fairly recent problem for Flint.
Can't you repubes ever learn how to Google?
Flint Water Crisis Fast Facts - CNN