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Water Quality Monitoring

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The health of the lagoon and reef is important for the welfare of the people. It is vital that the health of the lagoon is monitored and action is taken to protect the health of the lagoon, coral reef and the people that use it.


Human activities can contribute to poorer water quality, for example from waste from the farming of pigs, deforestation and farming crops close to streams.


“The water quality monitoring programme gives an evaluation of the state of the streams and the lagoon, and can be used to identify issues that need to be addressed”

The Ministry of Marine Resources in collaboration with the National Environment Service, Infrastructure Cook Islands and the Ministry of Health, undertakes the monitoring of stream, lagoon and groundwater in the Cook Islands.


The programme is supported by the European Union, Cook Islands Ridge to Reef Programme and the Mei Te Vai Ki Te Vai Project. 

The objective of the monitoring is to provide baseline data:

  • to assess the health of the lagoon
  • to provide information to make good management decisions.

The monitoring programme was initiated in 2004, and has been periodically audited by New Zealand’s National Institute of Water and Atmospheric Research (NIWA). Laboratory and sampling regime protocols are subject to regular developments along with continuous staff training to ensure the production of sound results.

The objective of the monitoring is to provide baseline data on:

  • Nutrients
  • Nitrogen (Ammonia and Nitrates ) and Phosphorous (Phosphates) are elements that can be found in fertilisers, washing powders
    and human or animal waste.  They are normally present in water in small amounts and are needed for the growth of plants and algae. If their concentration becomes high, an excessive amount of algae will grow which can be harmful to corals and be of public health concern.
  • Bacterial Pollution – A major concern worldwide regarding water quality is the pollution caused by human and animal wastes. The presence of bacteria Enterococci sp is monitored as an indicator of such a contamination. 
  • Oxygen Levels – The dissolved oxygen (DO) levels indicate how much oxygen is in the water. This oxygen is needed by the organisms living in the water and its amount follows a daily cycle. Low DO levels indicate a disturbance in the ecosystem such as an algal bloom.
  • Water Clarity – Assessed by two parameters: the amount of chlorophyll and suspended solids in the water.