In 1982, the UNC abandoned its Church Rock operation.
In 1983, due to the groundwater contamination, the operation was placed on the EPA's National Priorities List.
Yet that same year, federal and state authorities were still claiming the impacts the disaster had on people and the environment were minimal.
This wasn't the first time authorities had got it wrong about people dying from working in the domestic nuclear industry.
During the Cold War, hundreds of Native American miners died from cancer and lung diseases after working in the industry.
These deaths were scientifically linked to working with uranium, yet for years government agencies claimed no one had died or was harmed from working in the industry.
UNC also continued to dismiss claims of hardship from the Church Rock spill.
In 1983, despite locals noting their cattle kept dying after drinking from the water, Stanley Crout, a spokesperson for UNC, told the New York Times, "We just don't know of any substance to those claims."
Crout noted the reason the Navajos were concerned was because they didn't understand the effect of uranium.
Sources: New York Times, Vox, EPA, Science History, AJPH