BISMARCK, N.D., May 6 (UPI) -- For at least the fourth time in less than a year, North Dakota's government said it was notified by Oasis Petroleum of a spill of oil products near a lake.

The state Department of Health said it was notified by the company, which has headquarters in Texas, of a spill of so-called produced water in Burke County near the border with Canada.


"Although the exact size of the spill is not known at this time, it has impacted an unnamed tributary of Smishek Lake," the department said in a statement Tuesday.

The report is at least the fourth such incident of its kind tied to operations led by Oasis in the state. About 500 barrels of produced water, or brine, was spilled by the company from a pipeline in Burke County in April.

About 1,000 barrels of brine were spilled from a corroded pipeline at a well site owned by Oasis in McKenzie County in October.

Energy companies inject brine, or salt water, to improve oil and gas production from shale deposits. The Federal Environmental Protection Agency said brine may contain toxic metals and radioactive substances that can be "very damaging" to the environment and public health if released on the surface.

Oasis in February said it increased net daily production from its portfolio by 35 percent from 2013 levels to 45,656 barrels of oil equivalent last year. Close to 90 percent of that is in the form of oil. Full-year 2015 production is expected in the range of 45,000 to 49,000 barrels of oil equivalent per day.

Because of lower oil prices, the company said its capital spending plan for 2015 was 12 percent lower than expected.

The State Health Department said it and oil spill responders were on site observing the cleanup operation from the latest incident in Burke County. There was no statement on the incident from Oasis.