The company said Thursday the water spilled from a pipeline at its Belloy field in northern Alberta and hydrocarbons got into a small, unamed creek but there was no danger to the public and no sign of an impact on wildlife.
Apache Canada, the regional division of U.S.energy explorer Apache Corp., said the volume of the release was about 422,675 gallons, or the volumetric equivalent of 10,000 barrels.
Produced water comes from fluids extracted during oil and gas operations. It usually contains salt and other minerals along with oil and gas, but it's treated to remove recoverable hydrocarbons at the surface.
Apache Canada said it sent a team of environmental specialists to the site to take samples, map the affected area and begin cleanup efforts.
The pipeline, which was used for injecting water into oil and gas fields, was shut down and isolated after the incident, the company said. Alberta regulators were notified of the release and started their own emergency response plans.