ST. PAUL, Minn. (AP) -- Minnesota pollution regulators have denied a water quality certification for Enbridge Energy's proposed Line 3 upgrade, but it may be a short-lived victory for opponents of the project.

The Minnesota Pollution Control Agency announced the denial Friday. The agency said the move was necessary because the state Court of Appeals had ruled in June that the environmental review didn't address a possible spill in the Lake Superior watershed, among other things.

The MPCA says Enbridge can re-file for the certification.

Calgary, Alberta-based Enbridge says in a statement that it expects the Public Utilities Commission to go over what's needed to revise the environmental review at a meeting next week.

Enbridge says it needs to replace the aging crude oil pipeline for safety and to restore its original capacity. Tribal and environmental groups argue that the project risks oil spills in pristine areas.