Water quality indicators

Four key water quality indicators are assessed for the Darwin Harbour Report Cards.

 IndicatorParameterWhy is this important?
 Water Clarity


Light is important for microscopic algae and other plants, such as seagrasses, to grow and photosynthesize. Stormwater and dredging can reduce water clarity and affect plant growth.


Dissolved oxygen

Oxygen saturationOxygen dissolved in the water is essential for fish and other animals to survive. The amount of oxygen in the water can be reduced by water pollution.

Nitrogen oxide,
ammonia and soluble phosphorus concentrations

Nitrogen and phosphorus are nutrients required for algae to grow. However, high nutrient concentrations can increase the amount of algae, resulting in algal blooms which affect the broader environment.

Chlorophyll-a concentration

These are microscopic plants that may appear as specks in the water, or as a scum floating on the surface. Algae are an important part of the ecosystem in the harbour, but excessive amounts have a detrimental effect on the waterway.

Last updated: 18 August 2020

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