The allocation of an extra $16 million for ferry wharves at Kurnell and La Perouse means there is now $34 "in the kitty" for the much anticipated project.
Transport Minister Andrew Constance announced last week $16 million would be contributed to the works from a $205 million stimulus package for maritime works across NSW.
New wharves will allow the resumption of a ferry service across Botany Bay if an operator can be found.
Ferries used to run up until 1974.
A Transport for NSW spokeswoman has clarified the funding situation.
The spokeswoman said the $16 million injection took the total combined funding commitment from both state and federal governments to $34 million.
"The total estimated cost of the project will be confirmed following completion of the planning phase which is now underway," she said.
The spokeswoman said geotechnical investigations were being completed at both La Perouse and Kurnell to determine the conditions beneath the sea bed.
"Archaeological test excavations are also planned for the coming weeks, which will help determine the location of any significant heritage sites that may exist at the location of the proposed wharves," she said.
"The spokeswoman said the site investigations would inform the design and the environmental impact statement, which was being prepared to support applications for planning approvals that must be obtained prior to construction.
"The environmental impact statement will be placed on public exhibition in mid-2021 for the community to comment, and Transport for NSW is continuing to engage with key stakeholders and community groups," she said.
Building of the wharves is expected to take about two years from approval.