Scientists believe they have removed enough of a contaminant from one section of the aquifer at the Idaho National Laboratory to pause cleanup efforts and monitor water quality.

More than 50 years ago, workers in the Test Area North section of the INL began pumping the first of what could be thousands of gallons of a pollutant called trichloroethene into the Snake River Aquifer. Trichloroethene, or TCE, can cause cancer when ingested.

In 2001, the Department of Energy began operating a pump and treat system that has cleaned more than 350 million gallons of water to date. This week, officials will temporarily turn off the system in order to observe progress.