In 1969 investigations were again made into the suitability of the Parklands as a water source. The Department of Mines constructed an observation borehole 200 yards due south of the Golf House. The project was in connection with an investigation into the water resources of the sand beds of Botany Basin but investigators did not recommend any further research in the Parklands.
In 1972, as part of the Green Bans Movement across Sydney, a green ban was placed on Centennial Park. A proposal has been made to build a massive sporting complex at Moore Park as part of a tentative bid to host the 1988 Summer Olympics. The proposal covered 40 hectares of land, equivalent to 30 per cent of the entire Parklands.
Protests about this threat were led publicly by the likes of Nobel award winning author Patrick White, Neville Wran (who went on to become NSW Premier), high profile environmentalist Vince Serventy and countless other high profile people. Protesters very early had the support of Jack Mundey and the union movement. Mundey would later recall that the Chief-of-Staff of the Sydney Morning Herald said that the two issues that generated the most letters to the paper in 1972 were the Centennial Park proposal and the proposed removal of fig trees in the Domain.
As a result of the Green Bans and threats to places such as Centennial Park, the future government led by Neville Wran introduced heritage and environmental protection policies to the NSW Parliament, and Wran moved the administration for Centennial Park to his own Department.