(Reuters) - A team of U.S. regulators probing contamination at a Colorado gold mine accidentally released a million gallons (3.8 million liters) of orange-hued waste water containing sediment and metals into a local river system, the Environmental Protection Agency said on Thursday.

The waste water that had been held behind a barrier near the abandoned Gold King Mine spilled on Wednesday into Cement Creek, which flows into the Animas River in San Juan County, EPA spokesman Rich Mylott said.

Several workers were in the EPA crew that was using heavy equipment to pump and treat the waste water when the breach occurred, Mylott said, adding that none were injured.

Media images showed a trio of kayakers floating down a mustard-yellow stretch of the Animas River, near Durango.

"The primary environmental concern is the pulse of contaminated water containing sediment and metals flowing as an orange-colored discharge downstream," Mylott said.

Federal and Colorado health officials warned water users downstream to turn off intakes and avoid water-borne recreational activity until the contaminated water passes.

The city of Durango said tap water was safe for its water utility customers, saying in a statement it stopped pumping water from the Animas River and was instead drawing water from the unaffected Florida River.

The EPA said it would be sampling downstream locations to confirm that the release has passed and poses no additional concerns for aquatic life or water users over the coming days, though it expects a batch of results on Friday.

It also said it would assess damage near the mine and any residual releases of mine water.

(Reporting by Eric M. Johnson in Seattle; Editing by Eric Walsh)