The tribe at the forefront of fighting the Dakota Access oil pipeline has found evidence that more than a million gallons of drilling fluid leaked as construction crews tunneled under the lake that is the tribe’s main source of drinking water.
Authors of an engineering report filed last year in a North Dakota lawsuit estimates that 1.4 million gallons of drilling mud escaped the confines of the tunnel in 2017 — at the same time authorities above ground were breaking up the protests about the pipeline.
The report found no indication in the records of pipeline developer Energy Transfer that anyone checked to see if it had reached the lake, called Lake Oahe.
The Standing Rock Sioux Tribe says that amounts to violations of the environmental rules laid out for the construction project. Among other things, those rules called on construction crews to stop drilling and investigate when there were signs of leaks. Tribal officials say the Army Corps of Engineers, which controls the lake, never disclosed them.
