Multiple isolated riverside communities in outer Sydney will be cut off from the public transport network as ferry operators plan to strike over pay rates.
The Maritime Union of Australia organised the industrial action - which will run for 24 hours starting at 6am on Monday - in response to contracting company Birdon Group's refusal to raise wages above the industry minimum, union spokesman Paul Garrett told AAP.
"What workers are seeking is decent pay in line with the community expectations and inflation - the money is just not enough," he said.
The union had been negotiating with Birdon since September but the company was unwilling to compromise, Mr Garrett said.
"Birdon refused to put any wage increase on the table whatsoever."
The NSW Liberals criticised the planned strike, saying ferries were the only reliable transport option for some residents whose only alternative is a five-hour drive along remote roads.
"Monday's strike means workers miss shifts, kids miss school classes and families are forced to bear the brunt of both," opposition transport spokesperson Natalie Ward said in a statement.
Services will be affected in Berowra Waters, Wisemans Ferry, Webbs Creek, Sackville and Mortlake.
Member for Hawkesbury Robyn Preston expressed concern that emergency services will be unable to reach the otherwise-isolated communities.
"It isn't good enough that residents are being held to ransom ... police, firies and ambulance cannot be kept waiting for a ferry service to resume operation," she said.
However, the union has since pledged to send volunteer ferry operators to provide school trips and emergency medical transport throughout the strike.
"Many of the operators live in these communities themselves and know just how vital the ferry services are," Mr Garrett said.
"It's Birdon and Transport for NSW we want our action to target, not our families, friends and communities."
Birdon declined to comment and referred AAP to Transport for NSW.
Transport Minister Jo Haylen called on Birdon to reopen negotiations and come to an agreement with their workforce.
"That sets a pretty dangerous precedent if I was just to turn around and say 'here's another blank check'," she told Sydney radio 2GB.
"Ultimately they signed this contract, no one put a gun to their head."
