Renfrewshire Council has given the green light for work to start on the £3.6m third and final phase of the North Renfrew Flood Prevention Scheme.
But councillors had to agree to borrow an extra £2.1m to pay for it.
The scheme is designed to protect 350 homes in Renfrew from surge tides which can add more than two metres to the Clyde's normal high tide level.
Tender documents will now be prepared for a "large capacity pumping station", capable of clearing 1200 gallons of water a second.
It is needed because the Mill Burn cannot discharge into the Clyde during tidal surges or heavy rain, potentially causing localised flooding behind existing defences.
The work will also include commissioning flood barriers.
The first two phases of the project involved diverting the Mill Burn, building nearly a kilometre of earth embankments and dredging more than 10,000 tonnes of contaminated sediment from the ferry dock which was then filled in with imported material.
The North Renfrew scheme is part of a wider flood management policy designed to systematically reduce the risk of flooding throughout Renfrewshire. Flood defences are being backed up by steps to make sure drains, culverts and, in some cases, open watercourses are kept clear and free-flowing.
Councillor Eddie Devine, Convener of Renfrewshire Council's Environment Policy Board, said: "North Renfrew Flood Prevention Scheme is an important part of our strategy for protecting local communities.
"This scheme is part of our integrated approach to making sure Renfrewshire is properly prepared to cope with the kind of extreme weather that is becoming a fact of life.
"We are investing in flood defences and making sure that anti-flooding measures are included in new developments at the planning stage.
"We are also working closely with our partners SEPA and Scottish Water."
The council initially put the project out to tender in 2011 but was forced to abort the plan when tender returns "significantly exceeded" estimates, councillors were informed in a report.
The scheme has then redesigned to reduce the costs.
Current estimates say the scheme will cost £3.6m to complete.
The report to councillors said the reason for the increase in costs was construction inflation since 2004 when the first estimates were produced, combined with a better understanding of the complexity of the project as it progressed.