Officials are working to assess the extent of an oil spill reported by Nalcor at the Churchill Falls Switchyard earlier this week.

Nalcor says a transformer failed at the switchyard around 8:30, Thursday night, resulting in the release of oil contained within the transformer.

The transformer holds 53,000 litres of oil, and crews are assessing how much of that oil was released. Nalcor says on-site inspections have discovered no evidence of oil released into the Churchill River.

The product, known as Voltesso, is used in transformers and is biodegradable over a long period of time.

Booms have also been deployed on the Churchill River as a proactive measure to contain any potential oil in the environment.