Erosion along the North Otago coast, particularly from Waianakarua to north of Oamaru, has been a problem for decades and protection work has been carried out at some sites.
The latest plan is to call tenders for contractors to build about 400m of ''mattress protection'' along that stretch of foreshore, which a report recommended as the best solution.
Mattress protection places a gentle slope of protective covering over the erosion-threatened area. Under storm conditions, that becomes exposed but fills in again with sea gravel during calmer weather.
Other options looked at included an offshore breakwater or a seawall. While the cost of the work would not be known until tenders were received, the report said it could be carried out for about $700,000, within $800,000 already allowed in the budget.
Water services and waste manager Martin Pacey said that section of coast had suffered coastal erosion at about half a metre a year, but one single storm could cause up to 15m.
In recent years, it had virtually eroded all of the blue penguin reserve between Holmes Wharf and Oamaru Creek, including washing away part of its fence.
''Left unchecked, this erosion will threaten the penguin nesting area and recently capped contaminated land site where a timber treatment plant used to be,'' he said.
Various options for protection were investigated.
''The nature of the works is moderately complex and a high degree of experience and specialisation is required to mitigate construction risks,'' he said.
The assessment identified the mattress protection as the preferred compromise between cost and performance.
While it was the lowest-cost option, it did not score well on certainty and durability.
The assessment said the primary objective of the protection was to halt the loss of land to erosion. Others included creating improved access along the foreshore, establishing and retaining the beach, supplementing the penguin reserve and improving aesthetics.
