Warm water bore discovered on Waiheke

Waiheke Island could join Rotorua, Waiwera and Miranda as a spa resort after a promising discovery of warm water in a bore close to the ferry terminal at Matiatia.

Geologist Howard Alldred, of Geodata Consulting, said there was a "very good chance" of a commercial strike after a bore drilled to 100m at Matiatia produced water at 20C, twice the normal temperature at ground level.

"It's absolutely exciting. If it can be proven a commercial prospect then Waiheke suddenly has a winter tourist potential.

"Waiheke tends to go to sleep a bit during winter because there is not much on and the beaches are not that attractive," said Mr Alldred, whose postgraduate thesis was on the thermal waters at Waiwera.

Drilling further bores to a depth of 300m to 500m would determine if there was water at 50C to 60C - the level needed for a spa resort.

At Miranda Hot Springs, manager Kay Douglas said the water came out of the ground at 57C and was cooled in the pools to 36C to 39C, depending on the season.

Great Barrier Island has a hot water spring and there is anecdotal evidence of a hot spring on the beach at Owhiti Bay on the north-east corner of Waiheke, believed to be covered by sediment run-off.

News of the discovery coincides with plans by the Auckland City Council to buy the prime coastal gateway, including the "Harbourmaster" site where the bore xsits, from a private developer for $12.5 million.

Waitemata Infrastructure is quitting after stiff opposition and legal setbacks to a planned $35 million village of apartments, restaurants, bars and hotel accommodation at Matiatia.

Waitemata Infrastructure director Steve Norrie said a commercial hot water find would not affect the legally bound sales agreement.

"If they find something like that I guess that's their windfall gain," said Mr Norrie, whose company sank the bore about three years ago to provide water for its controversial development.

Mayor Dick Hubbard said it would be silly not to further investigate, given the potential commercial gains to the council and the island from a hot water strike.

The council has yet to decide on its plans for the land, which will include some commercial development.

Mr Alldred has written to Mr Hubbard about the potential at Matiatia, saying he believed the bore had penetrated the roof of a hydrothermal plume that was using a structural conduit to allow geothermally heated water to rise to the surface.

"The greywacke bedrock that lies beneath the Auckland region is riven with these fractures, and the hot springs at Miranda and Waiwera are examples," he wrote.

Mr Alldred told the Herald further analysis would determine the best places to sink further bores. He estimated the cost of drilling each bore 300m to 500m at $50,000 to $100,000.