BISMARCK, N.D. — The state Health Department says equipment failure was the cause of a 4,200-gallon spill of oil and saltwater at an oil well pad in Burke County.

The pad about 6 ½ miles southwest of Bowbells is operated by Cornerstone Natural Resources LLC.

Health officials say about 1,050 gallons of oil and 3,150 gallons of brine were released on Saturday. An unknown amount flowed into a nearby slough.

Work is underway to clean up the slough and contaminated soils. Health Department personnel have visited the site and are monitoring cleanup.