Apache said it was responding to the release of so-called produced water from its Zama production area in Alberta. The company said more than 250,000 gallons of produced water were released and remediation efforts were under way on more than 100 acres of land.
Apache described produced water as a mixture of oil, natural gas, salt and other minerals that are brought to the surface during extraction processes. It's treated to extract hydrocarbons.
"No injuries have been associated with this incident," the company said in a Wednesday statement. "The Zama River has not been impacted and there is no risk to the public."
The spill was discovered June 1. Aboriginal Chief James Ahnassay told The Globe and Mail newspaper "every plant and tree died" in the area. An Apache spokesman told the newspaper the water contained "trace" amounts of oil.
Apache said it's working with the Energy Resources Conversation Board and Alberta Environment and Sustainable Resource Development on site to determine the cause of the incident. It didn't explain why it waited until Wednesday to issue a statement.