16 September 2015

Water Quality of Concern in West Coast Harbours

eCoast Marine Consulting and Research has been awarded a contract with the Waikato Regional Council to undertake a major study investigating the physical characteristics of the West Coast harbours and estuaries, Port Waikato, Raglan, Kawhia, Aotea, Marokopa, Awakino and Mokau.

The study, which is currently underway and due to be completed in April 2016 aims to understand harbour circulation patterns, how water enters from rivers and gets exchanged with the open ocean, and how this impacts water quality. This will help to identify areas of the harbours particularly vulnerable to pollution from rivers, sewage spills or other sources of contamination.

eCoast senior consultant Dougal Greer who is leading the project notes that this is the first time research has been undertaken for many of the harbours on the West Coast of the Waikato.

“Historically research has been focused more on East Coast harbours, so it is great to see some attention focused on the West Coast and it’s exciting to be a part of it," says Mr Greer.

"As part of this project we have been consulting with local communities based around the harbours and they have all been very supportive of us doing this work."

The study involves mapping the sea floor in and around the harbours and measuring oceanographic data such as currents, sea level, water temperature and salinity.

A second part of the study will involve creating computer models of each harbour to simulate tidal and wind driven circulation patterns. Ultimately this will be used to understand how different parts of each harbour are flushed by ocean water.

While it is well known that the water quality in harbours is strongly affected by river inflows, which is in turn affected by land use activities upstream, the link between how the harbours are affected by land use is poorly understood, and Mr Greer says this study is huge step forward to changing that.

“Some of our preliminary results were quite surprising. We found that when it comes to faecal coliform contamination, the effect of recent sewage spills in Raglan Harbour was almost negligible when compared to what enters the harbour from rivers and storm drains after a heavy rain," he says.

"This is not to downplay the effect of a sewage spill, but it is also important to understand what else flows into our harbours on a regular basis”.

Greer and colleagues from eCoast will presenting results from this study at the bi-annual Coasts and Ports Conference being held from 16-18 September at the Pullman Hotel in Auckland.

eCoast Marine Consulting and Research is a small, independent marine and freshwater research consultancy based in Raglan on the west coast of New Zealand’s North Island.

As well as being life-long and passionate surfers and ocean enthusiasts, the company’s directors and employees all hold Ph.D.’s or other postgraduate qualifications in coastal science, oceanography, engineering, marine biology and mathematics. The group strives to be a world leader in sustainable coastal development and science based decision making in the coastal zone.

ENDS

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