South Australia's objections to an offshore wind farm in the state's southeast are at odds with its push for renewable energy jobs and plans to cut greenhouse emissions, unions say.
The Communications, Electrical and Plumbing Union of Australia, the Maritime Union of Australia, the CFMEU and the AMWU have condemned the state government's recommendation that an offshore wind farm zone not extend to Commonwealth waters off the state's southeast.
The unions say claims about potential harm to the rock lobster industry and marine life had jumped the gun, coming before any proper studies had been conducted.
"We know that rock lobster fishing and offshore wind coexist in other parts of the world," CEPU state secretary John Adley said.
"Uninformed knee-jerk decisions like this risk the state's broader economy and environment."
In its submission to the Commonwealth last week, the SA government expressed concern about the potential impact an offshore wind farm could have on the southern fisheries and marine environment.
As well as the rock lobster industry, it said the area was also home to other important fisheries including abalone, marine scalefish, and bluefin tuna, and was close to the state's marine park sanctuary zones.
Environment Minister Susan Close said the government was committed to renewable energy projects that improved SA's energy security.
"But we cannot support ones that have the potential to cause significant harm to local industries and the environment," she said.
"This is particularly the case when they have no net benefit to South Australians."
The minister said the energy generated within the zone would be connected exclusively to the Victorian power grid and the proposed declared zone, from Warrnambool to Port MacDonnell in SA, overlapped with an area recognised for its biological and oceanographic significance.
Further concerns were held for the proposal's impact on biodiversity, ecosystems, and on a wide range of wildlife, including pygmy blue whales, southern right whales, white sharks, the Australasian gannet, the wedge-tailed shearwater and several species of albatross.
But Maritime Union of Australia state secretary Brett Larkin said workers were shocked by the government's decision to oppose investment worth billions of dollars with the potential to create thousands of jobs.
AMWU secretary Peter Bauer said the future of manufacturing in SA relied on access to reliable, cost-effective energy sources.
"The government's opposition risks denying us the opportunity to develop good sustainable jobs, as well as being at odds with the state's renewable energy policies," he said.
CFMEU assistant secretary Marcus Pare said it was disappointing to hear the state government was turning on its commitments to greener energy alternatives.
"Achieving Australia's goal of net zero means that each state must play a role in supporting renewable projects like offshore winds, including South Australia," he said.