"It's a nationally significant Category 1 heritage building and the treasures in the Sarjeant collection have national and international importance.
"Sadly, there's a very high risk of catastrophic damage in a severe earthquake and the building needs a great deal of work to ensure it's safe for visitors and suitable for both storage and display of the collection."
The Sarjeant on the Quay is the temporary home for the gallery but Ms Main said the council and community now needed to refocus on bringing the Queen's Park building into the 21st century while also retaining its essential historic character.
"The significant funding set aside by the Ministry for Arts, Culture and Heritage for the redevelopment project recognises how much the gallery and its collection are valued and appreciated both locally and nationally," she said.
In addition to earthquake strengthening the 1919 building, a new wing would be built at the rear, so there would be no change to the existing building's famed skyline as viewed from the middle of the city.
A fundraising campaign led by the Sarjeant Gallery Trust had identified sources for approximately half the project's total estimated cost of around $28 million.
Funding would still be sought from central government, the Lottery Grants Board, trusts, individual philanthropy and corporate sponsorship.
Ms Main said the construction work would only start once the funds needed for the project had been raised.
The resource consent application, which includes a full description of the proposal and heritage and environmental assessments, can be viewed at www.wanganui.govt.nz, at the Wanganui District Council offices, or at the Davis Central City Library or Gonville Cafe Library.
Anyone can make a submission on the application by completing Form 13 online.
Printed copies of Form 13 are available from the council offices and should be sent to the Chief Executive, Wanganui District Council, PO Box 637.
More information about the gallery's redevelopment project and interim relocation is included in the Help Support Our Sarjeant brochure available from Sarjeant on the Quay.