Turbidity monitoring

When maintenance dredging is underway, this map shows the turbidity and temperature conditions in the harbour.

Turbidity can be caused by dredging but is predominantly affected by weather related events.

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How to use the map

What do the colours mean?

When the markers are green the turbidity is below all trigger values, if yellow turbidity is above Tier 1, orange above Tier 2 and red above Tier 3.

Whilst the dredging can impact turbidity, based on the year of baseline data we expect the biggest increase in turbidity will be caused by natural events like storms, high winds and large swell events.

How is the information used?

Monitoring buoys in the harbour provide a continuous flow of real-time information to a dedicated team of experts at LPC and to dredge operators. Their job is to monitor the water conditions and modify dredging operations to ensure water quality is maintained.

What happens if the triggers are exceeded?

Tier 1 and 2 triggers are warning levels to help LPC manage the dredging. If these are exceeded, LPC will work with Boskalis to reduce dredge caused turbidity. This may include changing speeds, dredging location or pumping rate.

The Tier 3 trigger is a compliance level. If turbidity exceeds this level for more than 7.2 hours in 30 days the dredger will cease dredging in that area. The dredge can still operate in other areas with normal levels of turbidity.

What about water temperature?

The map also shows real-time water temperature at the buoy locations, providing a useful indicator of conditions for recreational users of the harbour.

LPC also has a wave buoy at the offshore disposal ground www.lpc.co.nz/lpc/weather-forecast/offshore-weather/

Monitoring Buoys

Water conditions are monitored continuously and transmitted to satellite.

Cloud data processing

The collected data is processed and stored in a purpose-built cloud database.

Real time monitoring

LPC & experts monitor the data and modify dredging operations in response to turbidity, weather and tidal conditions.

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