In April 2014, during a financial crisis, state-appointed emergency manager Darnell Earley changed Flint’s water source from the Detroit Water and Sewerage Department (sourced from Lake Huron and the Detroit River) to the Flint River.[7] Residents complained about the taste, smell, and appearance of the water. Officials failed to apply corrosion inhibitors to the water, which resulted in lead from aging pipes leaching into the water supply, exposing around 100,000 residents to elevated lead levels.
According to the article, this all started in 2014 when the city cut corners on the water quality to save money.
Yes, but the city officials had their boss replaced by state with one who had a mandate to cut spending. Wikipedia does a better job of getting that part right: