By Laura Zuckerman
Jan 23 (Reuters) - Residents of a Montana town whose water supply was tainted by an oil pipeline rupture last week got the all-clear on Friday to turn taps back on, though some reported brown or black material spurting from faucets even after their pipes were flushed.
Drinking supplies for some 6,000 people in and around the community of Glendive became contaminated last Saturday when an estimated 1,200 barrels of crude oil was spilled into the Yellowstone River from a pipeline breach several miles upstream from the northeastern Montana town.
Initial testing of Glendive's water, which is drawn from the river, showed levels of benzene, a cancer-causing constituent of petroleum, well above levels considered safe for human health by the U.S. Environmental Protection Agency.
Results of subsequent testing released on Thursday showed that benzene levels had fallen to acceptable levels, and state regulators on Friday said an independent lab analysis confirmed the water was safe to drink after residents flushed their taps of any residual contamination.
But some residents on Friday notified regulators that dark-colored matter was issuing from taps at or near the end of the flushing procedure, state environmental officials said.
An examination of the material by the EPA showed it was sediment that built up in water pipes after several days of disuse and was unrelated to the oil spill, according to the Montana Department of Environmental Quality.
The number of residents affected by the dark ooze was not immediately known.
State and federal regulators advised residents to continue to flush taps and wash foreign material down the drain until the water ran clear.
It remained unclear what caused the so-called Poplar pipeline to rupture Saturday morning, spilling oil into one of Montana's premier rivers.
Responders have recovered more than 240 barrels of spilled petroleum, but cleanup efforts have been slowed by the pooling of oil beneath layers of ice.
The pipeline, which normally carries 42,000 barrels of oil a day from producers in eastern Montana and North Dakota, has been shut down indefinitely.
Bridger Pipeline LLC, the company behind the pipeline, has trucked tens of thousands of gallons of bottled water to Glendive since the town's drinking supply was deemed unsafe.
Studies show rates of leukemia are higher in people chronically exposed to high concentrations of benzene, according to the American Cancer Society. (Editing by Steve Gorman and Clarence Fernandez)