Sand mining threat to Mangawhai coastline

 

As an Auckland industrial company gears up to apply for more years of mining activity in Mangawhai waters, the concerns of a local environmental group are mounting for one of the area’s natural icons. 

Mangawhai Harbour Restoration Society (MHRS) have been monitoring commercial sand mining activities along the area’s coastline for the last 25 years, and chair Doug Lloyd says they are increasingly worried about the impact that consented nearshore sandmining is having on Mangawhai’s dunes.

“Mining is causing considerable erosion along the coast as the resource consent allows the excavating company to remove sand from a depth of ten metres, which is very close to our beaches,” he says. “This sand is gone forever, it cannot be replaced.”

Auckland based company, McCallum Brothers Ltd (MBL) have held rights to mine up to 76,000 cubic metres of sand per year from Te Arai and Pakiri waters since 2006. In order to support their new permit application to Auckland and Rodney District Councils, which expires in 2020, the company have been conducting technical investigations before an ‘Assessment of Effects’ can be finalised and consultation with relevant parties can proceed. If successful, MBL would legally be allowed to extract a further 1.9 million cubic metres of sand, more than the equivalent volume of Mangawhai’s sandspit, for another 25 years. 

MHRS allege the iconic dune is under threat from the mining as the sand, which is removed from the underwater seabed, is being replaced with sand slipping down from the Spit. 

“If allowed to proceed this will have a devastating impact on the coast, the harbour and all of Mangawhai… it is of great concern.”

Scheduled harbour dredging is an essential part of MHRS’s coastal management, clearing the estuary’s channels of large volumes of sand blown into the waters from the spit, and returning this sand back to the Spit to ensure the continued rebuilding of the dune and protection of the estuary and habitats of nesting birds including dotterels and fairy terns. 

Vegetation growth, such as the 10,000 and 15,000 pingao and spinifex planted over many years by MHRS and volunteers, also secures sand hill movements and assists with new dune development.

No dredged sand is removed from Mangawhai’s eco system, Lloyd says, which is vital as the sand at Mangawhai and neighbouring beaches is not able to be replenished. 

“Every grain of sand removed cannot be replaced, we have a set and finite amount to sustain our harbour with,” he says. “Without these considerable actions by MHRS, particularly the dredging, the estuary will once again fill with sand, and the spit will disappear… as it almost did before being saved by the Big Dig.”

Mangawhai’s stunning coastline. Dredging by MHRS keeps the channels wide and clear and the Sandspit replenished, however could the dunes be under threat if nearby sandmining continues? PHOTO/BARRY LYNCH