Newly leaked documents leave more questions about how and why the drinking water supply in the city of Flint, Michigan, was replaced with polluted and corrosive river water.

It had been reported that Flint’s water supply was changed to cut costs, saving the state an anticipated $6 to $8 million per year. According to an email leaked to Motor City Muckraker, however, that may not have been the case, detailing that there were other ways to cut costs that would not entail poisoning an entire city.

In the email, the then-Detroit Water and Sewerage Department Director Sue McCormick offered a proposal which would have saved Flint $800 million over 30 years; some 20% over what they saved from the switch to Flint River water.

“Proposal offers a today rate of water for Flint/Genessee of $10.46 as compared to $20.00 paid currently per Mcf — 48% less that could be realized nearly immediately and even more when compared to the increases coming with KWA,” the email read.

“When compared over the 30 year horizon the DWSD proposal saves $800 million dollars — or said differently, saves 20% over the KWA proposal.

In a statement, McCormick explained that these savings “were due largely to three factors: 1. Flint’s move to a model contract that is currently used by all wholesale customers as opposed to its then current, but outdated contract established in 1965; 2. Changing the point of connection where Flint receives DWSD water, which reduces elevation and distance (both factors in determining cost); and 3. An agreement recognizing that should Flint invest and keep their existing water plant certified and operational as an appropriate system back-up source, the proposed costs recognized that DWSD would no longer include planning for redundancy in service, resulting in an offsetting credit.”

These details were not included in a state of the union address given by Governor Rick Snyder last Tuesday.

The problem with Flint’s water began in April 2014, when the city stopped receiving its supplies from Detroit, instead shifting to water from the Flint River, which is known to have a high corrosive salt content. Corrosive salts in the water damaged the pipes, which contain lead, causing that material to be released into the water, and contaminating it.

Flint city emergency manager Darnell Earley, appointed by Republican Governor Rick Snyder, was responsible for the shift.

In October, the state changed the city’s drinking water source back from the corrosive Flint River to the Detroit water system, but warned that the water is still not safe.

Several lawsuits have been filed in relation to the polluted water. Drinking water in city homes has been found to contain lead levels high enough to be declared “toxic waste” by the Environmental Protection Agency. Many have called for Governor Snyder to not only step down, but to be arrested for his lack of oversight.