The sinkhole, wider than a football field, swallowed 100-foot-tall cypress trees and caused the evacuation of many people who live in the area about 30 miles south of Baton Rouge, CNN reported.
When measured Monday, the hole was 324 feet in diameter and generally about 50 feet deep although at one corner it goes down 422 feet, said John Boudreaux, Assumption County's director of the Office of Homeland Security.
Residents said they noticed bubbles in the water for more than two months before the sinkhole opened up Aug. 3.
Sheriff Mike Waguespack and residents charge the Department of Natural Resources "knew for months" of integrity problems with a salt cavern 100 feet away operated by Texas Brine.
The cavern contains brine, salty water used to make chlorine and caustic soda.
Wagnespack said the sinkhole is dangerously close to a well containing 1.5 million barrels of liquid butane.
The DNR and Texas Brine were sued this week by landowners near the sinkhole who say their drinking water has been contaminated.