WILLISTON, N.D. – A spill earlier this month from a saltwater line not even a year old north of Williston has turned out to be the biggest spill of North Dakota’s current oil boom and may be one of the biggest ever.

About 70,000 barrels, or nearly 3 million gallons, of the brine escaped a rupture in a gathering line operated by Summit Midstream subsidiary Meadowlark Midstream.

Brines are also referred to as “produced water,” which is extracted along with oil and gas during exploration and production.

The company has been using vacuum trucks to suck about 65,000 barrels of water from the creek – but a significant amount of that is likely freshwater that was there before the spill.

“The problem is that ... the creek bed is kinda being replenished with water so we extract, it fills; we extract, it fills,” said John Morgan, a spokesman for Summit Midstream.

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The spill, discovered Jan. 6, originated in a rupture just west of U.S. Highway 85 near Blacktail Creek. It spread to the Little Muddy River where the creek connects.

Officials haven’t seen an effect on wildlife yet, but the full impact won’t be apparent until the ice melts in the spring, said Dave Glatt, environmental health chief for the state Health Department.

The highest chloride concentration the health department has found was nearly 92,000 milligrams per liter in Blacktail Creek close to the pipeline break. Normal levels of chloride are between 10 and 20 milligrams per liter, Glatt said.

The concentrations decrease farther downstream in Blacktail Creek and the Little Muddy River.

Chloride, ammonia and other contaminants in brine threaten life underwater.

“That has the ability to kill aquatic life and so we’ll want to see if the aquatic life was able to get out of the way, and if they weren’t, how badly they were impacted,” Glatt said.

Meadowlark has hired Stantec to assist with the emergency response and the long-term remediation. A third-party company is inspecting the pipe to find the cause of the rupture.

The 4-inch pipeline was installed in June 2014, according to Meadowlark.

Alison Ritter, spokeswoman for the state’s Department of Mineral Resources, said the last saltwater spill she remembers of this magnitude was in 2006, when a Zenergy Inc. pipeline ruptured and released almost 1 million gallons of saltwater into Charbonneau Creek near Alexander.

The saltwater in that spill killed fish in the creek and forced ranchers to move cattle, and remediation is ongoing.