Officials at the Sanford Underground Laboratory at Homestake say the water level dropped a record 23 feet during continued pumping the past week. Water is now 40 feet below the critical 4,850-foot level, where the first major physics experiment will be installed.

The South Dakota Science and Technology Authority is reopening the former underground gold mine to convert it into an underground lab, first at the 4,850-foot level. Eventually, a federal lab could be opened at the 8,000-foot level.

Water began rising in the mine after it was closed in 2003.

Pumps that were turned on more than a year ago have dropped the water level 360 feet.