Land slips on Maungawhau/Mt Eden have prompted a call for the Government to help ratepayers with a $1.2 million bill for urgent restoration work on Auckland's volcanic cones.
Two collapses of the rocky slopes, although small, showed the sensitive nature of the city's volcanic cones after decades of neglect, said Friends of Maungawhau chairman Kit Howden.
Erosion was "nibbling away" at the mountain and undermining trees.
The latest slip was 10 days ago in Rautangi Rd. An Auckland Council spokesman said the area was secured and did not pose a risk to visitors, who could still reach the park via the staircase.
Mr Howden said Mt Eden's disused quarries in particular were subject to slips.
Council staff did a good job with limited resources but more financial support was needed, he said, especially as the Auckland volcanic cones were being proposed for Unesco world heritage status.
Better care of the reserves was expected under a new Maunga Authority for 12 of the cones.
From next month, it will direct routine management by the council and possibly planting of a replacement tree on Maungakiekie/One Tree Hill, which has been bare since 2000.
But council parks, sport and recreation chairwoman Christine Fletcher said: "There is a huge amount of restoration work to be done - we estimate that $1.2 million of work needs to be undertaken immediately.
"It's going to be extremely hard to fill the aspirations of iwi and the community when there are no funds available."
Mrs Fletcher said the Crown should at least share the costs when it was transferring liability to local government.
The authority was set up under Treaty of Waitangi redress legislation passed last month. It gave significant cones to the Tamaki Collective, made up of 13 iwi and hapu.
Treaty of Waitangi Negotiations Minister Chris Finlayson said the Crown and Auckland Council had agreed the council would pay for maintenance work for the maunga, as it did before the settlement.
But under the settlement, revenue derived from the maunga through items such as leases, licences and concessions would contribute to the maintenance costs.