After a series of serious erosion events in recent years stripped sand from Dunedin's Middle beach, threatening nearby infrastructure, council staff are now keeping a close eye on creeping erosion at Waikouaiti beach.
Unusually high tides - including July's king tide - and storms in the past two months had combined to claim 5m of sand dunes, and washed away pine trees and 3500 plantings added over the past three years.
The gap between the beach dunes and nearby Matanaka Dr, running parallel with the coast, had reduced to between 3m and 5m as a result, council parks and reserves team leader Martin Thompson said.
The erosion was worst towards the eastern end of the beach, near the Hawkesbury Lagoon, although some sand had returned - in a process known as accretion - in recent weeks, Mr Thompson said.
Cr Andrew Noone, the Waikouaiti Coast ward representative, said the pine trees were not a significant loss for the stability of the dunes.
However, the 3500 pikao plantings - which had cost the council about $6000 - had been added in an effort to protect the area from erosion and it was "a little bit sad" to see them lost, he said.
"Council has, over the last three years, planted a considerable amount of those sand hills, obviously to help stabilise that area.
"Having them washed away is pretty disappointing," he said.
Council staff were monitoring the area, concerned parts of Matanaka Dr "could be threatened" if the erosion continued, he said.
However, it was too early to say whether more extensive - and expensive - beach protection measures would be needed, as was already happening at Dunedin's Ocean beach, he said.
"God knows what Mother Nature will throw at us going forward . . . The next cycle may well replace a lot of the sand - fingers crossed.
"That will really determine whether council will need to consider whether there's a . . . Middle beach scenario or not.
"At the moment, we have got a little bit of a backstop, but who knows what will happen over the next six to 12 months," Cr Noone said.
Mr Thompson said staff were monitoring the beach weekly but, despite the losses, were "not overly concerned" by the erosion yet.
The nearest sporting facilities were "20-plus metres back" from the seaward edge of Matanaka Dr, unlike Middle beach where sports fields and other infrastructure were built to the edge of the dunes, he said.
