BAILEYVILLE – A backed-up line at Domtar Industries Inc. resulted in a minor spill of sanitary wastewater into the St. Croix River, a company spokeswoman said Monday.

Gaile Nicholson said the release occurred Friday afternoon as workers were installing a sump pump in the plant’s septic system.

The line that carries filtered sanitary water from a holding tank backed up and the sanitary water mixed with groundwater in the bedrock and discharged to the river, she said.

Nicholson said the company estimates the total discharge – including groundwater – was approximately 200 gallons.

“We were discharging 2 to 3 gallons a minute into a flow of 3,635,000 gallons a minute,” she said.

The incident was reported to the state Department of Environmental Protection, she said.