In January, a pipeline leak caused nearly 3 million gallons of mining wastewater to contaminate major creeks and rivers in North Dakota.

It turns out, the company meant to oversee the project was opting not to use a monitoring system that was already in place.

According to the Dickinson Press, North Dakota regulators say Meadowlark Midstream had people checking pipeline meters in person, rather than using a remote monitoring system that was already installed.

The leak was found on Jan. 6 about 18 miles north of Williston, the Williston Herald reported, and quickly contaminated Blacktail Creek and Little Muddy River.

Eleven days later the runoff had reached the Missouri River, which PBS noted is a source of drinking water for one of the nearby towns.

What spilled isn't oil. It's a substance called brine, which is essentially the waste that is made after drilling. It can include very high concentrations of salts, The Associated Press says, enough to kill vegetation and make it unsafe for drinking. The brine can also include metals, petroleum, hydraulic fracking liquids and other potentially hazardous materials.

The Wall Street Journal said it's the largest spill of the wastewater in the state's history.

From 1995-2014, there were a total of 57 "significant" pipeline incidents in North Dakota, resulting in one death, five injuries and more than $41 million in property damage, according to federal data.