Mangawhai sandspit under threat: Sand mining company denies impact

A surfer on the Pakiri coast is dwarfed by McCallum Bros' sand mining vessel. Photo/ Doug Moores

Mangawhai sandspit has recently been confirmed to have lost more than 420,000 tonnes of its locally-unique non-replenishing sand. Local Democracy Reporting Northland reporter Susan Botting explores in a two-part series how those connected with the rare landform view its health and what is on the line. Today she explores tensions around sand mining.

A seabed sand mining company working off the Mangawhai-Pakiri coastline for more than 80 years is challenging critics who say the sandspit is being hit hard by its actions.

Scientists and local leaders have raised fears for the health of the Mangawhai sandspit as they say large amounts of sand have been lost over time.

McCallum Bros chief operating officer Shayne Elstob said as far as he was aware there was no presented evidence that showed sand extraction affected the sandspit.

Recent Mangawhai Harbour Restoration Society (MRHS) research showed 420,000 tonnes of sand have been lost from the sandspit in the past six years.

MHRS chair Peter Wethey said seabed sand mining had impacted the spit.

Mangawhai Harbour Restoration Society chair Peter Wethey. Photo / Susan Botting - LDR Northland

Dr Terry Hume, research lead coastal geomorphologist and former University of Auckland professor, said mining influenced the sandspit due to coastal processes such as wave action and seabed sand movement.

He said the quantity of sand lost from the spit was the equivalent of skimming 8cm of sand off the roughly 3 sq km land feature.

The Environment Court turned down a McCallum Bros sand mining consent application renewal last May.

In an agreement, McCallum Bros is allowed to continue sand mining in the Mangawhai-Pakiri embayment until May next year at the latest.

Elstob said the company had appealed that decision and would challenge it before the High Court later this year.

He said the High Court outcome would influence whether the company stopped sand mining in the embayment altogether.

The outcome of the Fast Tracking Act panel’s decision on the company’s sand mining consent application further north in Bream Bay would also influence its future embayment extraction.

Elstob challenged the March 2025 Mangawhai sandspit research, saying there were two different survey methods used in showing the sand loss.

Looking east across Mangawhai sandspit where sand from adjacent Mangawahi Harbour is piped onto prescribed locations under a formal Department of Conservation concession. Photo / Susan Botting - LDR Northland

“Until a repeat survey is undertaken using the same technology the volume stated should be treated with some caution.”

He said there had been agreement from all coastal process experts at the Environment Court hearing that extraction from the offshore zone - which was at least 2km from shore - “posed little to no risk” to the Mangawhai-Pakiri embayment.

Elstob said the company was currently mining in the embayment’s southern end, some distance from the sandspit. This was in Auckland Council’s jurisdiction. It had not mined in the northern Northland Regional Council (NRC) jurisdiction where Mangawhai sandspit was.

“Our ongoing topographic monitoring of the coastline does cover half of the shoreline of the Mangawhai spit and we have not seen any changes to the shoreline that could be attributed to sand extraction.

“Instead they have been related to some of the extreme storm events we have been having in recent times,” Elstob said.

NRC in 2021 warned the nationally important sandspit was at risk of erosion from seabed sand mining.

Kaipara District Council opposed Auckland Council extension of the activity’s consent at the same time.

Professor Mark Dickson, University of Auckland coastal geomorphologist, said seabed sand mining was among factors influencing the health of the Mangawhai sandspit in what was a “hotbed of coastal management considerations”.

Northland coastal engineer Andre LaBonte says Mangawhai sandspit’s health was regressing after almost three generations of adjacent seabed sand mining.

LaBonte said the situation was serious.

He said McCallum Bros seabed sand mining, which started in 1953, had seen the equivalent of roughly the sandspit itself above the high tide mark mined out of the Mangawhai-Pakiri embayment.

“Mangawhai sandspit is not holding its own. It’s only thanks to the local community’s efforts that the situation is not worse,” LaBonte said.

Elstob said it was not balanced to solely blame McCallum Bros for any perceived failing sandspit health.

There had been up to four operators extracting sand since 1953, a number of whom had had coastal permits to extract sand from the Mangawhai spit and entrance.

Hume said the sand in the sandspit was linked to the beach and sea bed through coastal processes.

Researcher and former University of Auckland professor Terry Hume talks about Mangawhai sandspit to a recent community meeting in the coastal settlement. Photo / Susan Botting

He said the quantity of sand lost amounted to 1.8% of the spit’s total volume.

Hume said he was most concerned about the loss further lowering existing surface depressions, making them more vulnerable to inundation from the sea.

Mangawhai resident and former Kaipara Deputy Mayor Richard Bull said ongoing seabed sandmining had undoubtedly impacted the landmark feature.

“We used to look out over the spit and out to the Hen and Chicks from our home and only be able to see a tiny bit of the Pacific Ocean. Now we can see heaps, four times as much sea,” Bull said.

Bull’s family sold the sandspit to the Government in the 1980s.

■ LDR is local body journalism co-funded by RNZ and NZ On Air.