The council had until Friday to agree to to $24 million for projects in Westport, Greymouth, Hokitika and Franz Josef.
At a special meeting last week, it reviewed feedback from the affected communities after a speedy round of public consultation over ratepayers' share of the cost.
Operations manager Randall Beal told the council that more than 60% of Westport and Hokitika people who responded were in favour of the projects and the proposed rating districts that would help pay for them.
In Franz Josef, the site of the biggest project, only 45% approved.
Another 18 percent of residents were in favour of the $18 million project, but still gave it the thumbs down, Beal said.
Some wanted the New Zealand Transport Agency to have no part in the project because they believed the transport agency's previous flood protection work for the highway and Waiho (Waiau) River bridge had made things worse.
Others wanted local ratepayers on the governance body for the rating district rather than just councillors.
Some were concerned about the term of the $1.9 million loan to cover the ratepayers' share of the so-called 10-year community resilience plan.
The loan would be paid back by ratepayers over 20 to 25 years, not 10 as some had thought, Beal clarified.
"And we can't go ahead without NZTA - they are the major partner in this. That is non-negotiable for us, for the government and for the ratepayers."
The project includes the raising of the Franz Josef bridge and its approaches on State Highway 6, raising existing floodwalls by 2 metres, and building new ones.
At one point in the meeting, one of the biggest chunks of funding to come to the West Coast in years appeared to hang in the balance.
Westland councillor Stuart Challenger said he could not vote to go ahead without a majority of the Franz Josef community in support, and he felt the proposal needed more work.
"Only 33 percent support the governance structure. We need more people to be in favour. Can we delay this and do more consultation?"
Councillor Laura Coll McLaughlin said she was reluctant to vote in opposition to Challenger as a constituency councillor, and her Buller colleague John Hill said he had promised electors he would never vote for a project with less than 50% support.
Councillor Brett Cummings warned that if the council missed out on $18 million of government funding, Franz Josef people would soon be coming to it saying they needed to extend their flood banks and would have to pay for it all themselves.
Westland's other councillor Debra Magner suggested the way through would be to add a Franz Josef community member to the rating district committee, and ensure the community was consulted about the strategy and action plan for the flood works, to allay concerns about NZTA.
Councillor Peter Ewen said it was a dilemma but the council needed to make a good decision.
"The smaller details, we can work around in the community - I can't see anything there that's a game-stopper."
In the end the council decided to take the money and run with the project that will buy Franz Josef 10 years to migrate north to higher ground.
The vote was 4-2 in favour, with Challenger and Hill opposed, and McLaughlin abstaining.
By Lois Williams
Local Democracy Reporting