Woodside Energy’s plan to drill for gas off Western Australia’s north-west coast could significantly damage “exceptional” coral reefs and it may be impossible to reduce the risk of an oil spill to an acceptable level, according to advice from the state’s independent environmental watchdog.

A draft letter from WA’s Environmental Protection Authority written in 2023, seen by the Guardian, sharply criticised Woodside’s proposal to develop the Browse gasfield, saying its plans to protect endangered turtles and blue whales near Scott Reef would be ineffective.

Woodside, Australia’s largest fossil fuel company, is hoping to win approval next year to develop the Browse basin, about 300km off the Kimberley coast. Scientists have warned it could damage the Scott Reef ecosystem, which is home to more than 1,500 species, many unique to the area.

EPA staff presented the draft letter to the authority’s board for approval in December 2023.…