Powerful storms in July this year swept an estimated 7 metres of sand off the eastern end of the beach and left four houses within 7m of the edge of a steep, scoured-out sand bank.
One of the houses was perilously close to the edge and three neighbouring houses were within 7m of the top of the bank.
Coastal scientist Jim Dahm said unless action was taken, the dune face would gradually collapse to a more stable slope resulting in the loss of more land.
The erosion was the worst at the eastern end of the beach since at least the 1950s and another storm like the ones in July could take another 7m, seriously damaging at least three and probably five houses, Mr Dahm said.
Spokesman for the owners of the worst-affected house, Don Pinny, of Ohaupo, said things seemed to be moving very slowly.
"We were led to believe remedial work would be done straight away, but they're very slow with coming to terms about what they're going to do."
Mr Dahm said sand had already been returned to the beach and planting grasses in a year or two when it settled would help prevent further erosion and allow the dune to recover if erosion occurs.
A total of 29 beach-front properties are at risk, with 10 at severe risk.
