Council's infrastructure director Phil Hoare said initial planning for the replacement of the bridge over the Goulburn River had commenced.
“The bridge is approaching the end of its life,” he said.
“The ultimate replacement of the bridge is anticipated to occur in five to 10 years, however could be earlier if funding is secured.”
Council's previous preliminary estimates put the cost of replacing the bridge about $7 million.
But Mr Hoare said the cost was now likely to be between $10 million and $20 million.
“The details and configuration of a replacement bridge have not been established yet however two lanes would be desirable,” he said.
Watt Road Bridge will also be closed to traffic from Monday, July 13 for about a month to undertake repair works to ensure the bridge is usable until its replacement.
Stage 1, predicted to take four to five weeks, includes the removal of the bridge's asphalt surface for inspections, followed by the replacement of the deteriorated timber beams and reinforcement of the connection to the substructure.
The next two stages, each taking four to six weeks, will involve inspections and repairs of lower and upper piles and remaining components, according to the council's website.
The estimated cost of the repair is $250 000, with $200 000 allocated towards the repair in the 2020-21 budget.
While work is going on, Mr Hoare said it was important people complied with load limit restrictions.
“To ensure the bridge remains operational until its replacement it’s important that users of the bridge comply with the load limit restrictions, as overloading places significant stress on the bridge, puts its structural integrity at risk and ultimately reduces its useful life.”
Watt Road Bridge was originally built in 1877-8 as a timber trestle bridge using timber from an earlier bridge (Tanner's Bridge) across the Goulburn River.
Mooroopna-Kialla Bridge originally had a central drawbridge that could be lifted to allow the passage of steamers to and from Echuca between 1875 and 1904 until it was replaced with a rigid centre section some time later.
The replacement section was badly damaged by floods in 1974 and was rebuilt.