The most recent report on the Waiho confirmed that raising the stopbank would be a short-term solution at best because the riverbed would continue to rise, O'Connor said.
"Physics would say it's impossible to hold back that river forever, and my frustration is that the council has continued to allow investment in homes and buildings on the south side when the long-term plan for the area is likely to mean some kind of withdrawal."
National Party list MP Maureen Pugh said the Government needed to make up its mind about the future of farms being repeatedly hammered by the river.
Under NZ First's "shovel-ready" initiative, the previous Labour-led Coalition promised funding to extend stopbanks on both sides of the river, but after the election, the new Labour Government confirmed funding only for the north bank, and the township.
Pugh said since then the wild river had caused massive damage to one of the most productive dairy farms in the district, destroying pasture on the south bank and leaving it strewn with rocks and debris.
"This has happened more than once and it costs heaps to fix - not to mention having to buy in feed and send cows away for grazing - these people need to know what their future is. "
If the Government was planning to let the river take the south bank it should let the community know, Pugh said.
"This has dragged on now for 18 months. If they're not going to honour their promise they should front up and say so."
The West Coast Regional Council, which builds and owns the stopbanks has research showing the bed of the Waiho is rising year on year, built up by gravel and rock washed down from the mountains as the Franz Josef Glacier retreats.
The question of whether to go on extending the floodbanks or let the river have its way and fan out across its natural flood plain has been under discussion for some time in official circles.
Pugh said the landowners were entitled to some certainty about their future.
"It's cruel to let people go on spending money on their farms if the Government is just going to abandon them."
It would cost $80 million to $100 million to buy all the farms out, and it was uncertain if that was what the Government was considering, Pugh said.
"I have sent in some written parliamentary questions for the Government, asking if they're going to honour their original commitment, and what their intentions are for the landowners."
Dairy farmers Neil and Kath Frendrup lost 15 paddocks in the most recent flood in early December, when more than 400mm of rain fell in the catchment over seven days, and the river swept around the end of the stopbank and on to their farm.
The damaged land was part of a hundred hectares devastated in the big flood of 2019 when the couple had to take out a loan to have their pasture re-established.
The regional council has offered to build a temporary stopbank extension for the Frendrups for $200,000 while they wait for the Government's funding decision.
