The state government has given final environmental approval for the Chevron-led Wheatstone liquefied natural gas (LNG) project in the state's northwest, tipped to cost $25 billion.
WA Environment Minister Bill Marmion said approval has been granted with 25 conditions protecting marine fauna, including whales, turtles and dugongs.
The proposed LNG plant will be built 12km south of Onslow in the Pilbara. The project initially will have capacity of 8.9 million tonnes of LNG per annum, plus a domestic gas plant though the environmental approval is for the processing of up to 25mtpa.
"The state government will continue to ensure the highest environmental standards are applied to project the local community and its environment," Mr Marmion said in a statement.
"This is a huge development for Western Australia.
"At its peak, the construction workforce for Wheatstone is expected to reach 3000 people, in addition to a further 3500 indirect jobs and billions of dollars in locally purchased goods and services," the minister said.
The environmental conditions stipulate immediate suspension of dredging if coral outside defined zones was damaged, no night blasting during peak nesting and hatching seasons for marine turtles and no piling work at night during the southern whale migration.
The approval also requires $13 million in environmental offsets, including $3.5 million over four years to improve management of critical habitats for humpback whales, dugongs and snubfin dolphins in Pilbara waters.
It also requires reductions in greenhouse gas emissions through offsetting about 2.6 million tonnes per year of reservoir carbon dioxide emissions.
Chevron Australia Managing Director Roy Krzywosinski welcomed the approval and said the company looked forward to a timely environmental approval from the federal government.
A final investment decision on the project is expected later this year.
The Wheatstone project is a joint venture between the Australian subsidiaries of Chevron (73.6 per cent), Apache (13 per cent), Kuwait Foreign Petroleum Exploration Company (7 per cent) and Shell (6.4 per cent).
