"Managed retreat" has become the catchcry of councils struggling with eroding coasts. But it will never be popular with beachfront bach owners.

At Buffalo Beach, Whitianga, the council has drawn a "hazard line" through the middle of frontline properties.

But at Waihi Beach, residents have persuaded the council to support new protection works, after it proposed moving houses back from the beach.


"Worldwide, there is a move away from rock walls which degrade beaches," says Jim Dahm of Coastline Consultants, a former Environment Waikato staffer.

While seawalls protect the properties behind them, when the waves advance they often undermine the walls and carve out the beach. The seawall blocks the natural exchange of sand between the sea and sand dunes.

"On the east coast of the US, there have been a number of settlements on very lovely barrier islands," Mr Dahm says.

"A lot of those states have gone completely away from rock walls, and extensively manage the coast by placing sand."

At Waihi Beach, the Western Bay of Plenty District Council's district plan in 1994 proposed a "coastal protection area", defined by Waikato University's Professor Terry Healy, which extended up to 137m inland from the toe of the beach foredune.

In the "primary" protection area, covering 325 beachfront properties, the council allows new buildings only if there is written confirmation from a building removal firm that the building could be moved if major erosion occurs.

In the "secondary" protection area, covering essentially the second row of houses, new buildings are a "restricted discretionary" activity, requiring specific planning consents.

Dr Healy believes this precautionary approach is justified by recent history.

"At the time of subdivision in the late 1940s-early 1950s there was a 56m esplanade reserve including a high frontal dune - which some property owners lowered by bulldozer to get a better sea view - between the property boundaries and the mean high water mark along Shaw Rd," he says.

"Now the boundary is the sea wall."

Not only has the sand dune gone, but at high tide the entire beach is often underwater up to the rocks that protect the houses.

At Bowentown, just south of Waihi Beach, the dunes retreated a massive 90m during the 1960s and 1970s, when weather patterns were last in a phase when there were more La Nina events, with northeasterly winds cutting into the Bay of Plenty beaches.

Right at the end of this phase, with the dunes almost completely denuded, a big storm in July 1978 caused damage right along the coast. A house at Waihi Beach almost toppled into the sea a year later.

In the following 20 years, southwesterly El Nino winds dominated over the La Nina pattern and the Bowentown dunes grew out again by 70m. Residents relaxed.

But experts believe we have switched back into a predominantly La Nina pattern since 1998 - a pattern which may persist for 20 to 30 years.

As Dr Healy puts it: "The Bay of Plenty coast may expect more and enhanced stormy wave erosive conditions over the next 25 to 35 years or so, and this would facilitate major shoreline retreat into developed areas."

That is a prospect which Robyn Ross and partner Dave Ingle, whose spacious house sits directly above the Waihi Beach seawall, do not accept.

Ms Ross, who has done environmental consulting for the World Bank in Africa, and Mr Ingle, the general manager of the Waihi goldmine, are fully aware of the risk they run in living by the sea.

"In an ideal world you wouldn't permit houses to be this close," Ms Ross says.

"But we are here. We say we'll maintain the seawall. What's your problem?"

Ms Ross and Mr Ingle are not the only influential residents. Governor-General Silvia Cartwright and husband Peter have a house within the primary protection area in Ayr St; Helen Clark's parents are around the corner in Seaforth Rd; Sir Edmund Hillary has a place on the beachfront.

As stated to the Environment Court last year, the Western Bay council's policy was to "promote the voluntary relocation of houses within existing property boundaries" and to "maintain the existing seawall for health and safety purposes only" - in other words, to remove jagged edges, but do little more.

But after six years of pressure, the council's directions committee finally reversed direction on December 6 and agreed to go to tender on designs for "protection works" to "provide protection whilst enhancing the amenity value of the beach".

According to Ms Ross, council policy analyst Grant Bridgwater told councillors they would be "going backwards" if they adopted the new approach.

Mr Bridgwater says it is probably not possible to design something within the budget of $1.91 million that can both protect properties and enhance the beach.

However, Ms Ross and Dr Healy both believe it may be possible to build a series of underwater sand reefs that would keep more sand on the beach - and thereby help to protect the properties behind it - for less than $1 million.

Ms Ross says the beachfront owners will pay for any protection that benefits them alone, although they say the community should share the costs if it also benefits.

The council's December 6 decision says the beachfront owners should pay 90 per cent of the protection costs.

Whatever the final details, Ms Ross' group seems to have won this round in principle. "Managed retreat" has itself retreated before the practical realities of what former Prime Minister Sir Keith Holyoake once called our "property-owning democracy".

* Tomorrow: Papamoa fights back.

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