About 3,000 litres of "non-hazardous" oil spilled into the St. John River at Mactaquac Generation Station last Friday, NB Power has announced.
A broken seal on an underwater turbine hub caused the release of Teresso 32, which is a lubricating oil.
The oil is biodegradable, has a low eco-toxicity, and is "not expected to be harmful to aquatic organisms," the utility said in a statement on Tuesday.
“While this incident is expected to have minimal impact on the natural environment, given the type of material released and the high river flows at the time of the incident, we are advising the public as a precaution and out of respect for those who live and work near the river,” said Keith Cronkhite, vice-president of generation and business development for NB Power.
The release was immediately reported to federal and provincial environmental authorities, said Cronkhite.
A licensed cleanup contractor was called in, but fast-moving spring river flows quickly moved the oil downstream, "making it impossible for cleanup crews to collect and remove the material," he said.
Work to repair the broken seal is ongoing. NB Power hopes to bring the turbine unit back online as quickly as possible.
Crews were alerted to the problem by an alarm in the station's fourth turbine and shut down the unit, preventing further release.