Lake Rotoroa

Water quality indicator for public health

The water quality in Lake Rotoroa is subject to seasonal changes. At certain times of the year or under certain weather conditions the lake may be prone to algal blooms or high levels of bacteria, which result in poor water quality. 

The quality of the water is actively tested and monitored by the National Public Health Service for potential health risks through manual grab sampling, with a water quality indicator system in place to inform the public of any potential health risks.

• Low Risk – when at Low Risk, the public are advised to not drink the water 
• Caution – when at Caution, the public are advised to not drink the water, enter the water or allow their pets to enter the water 
• Alert – when at Alert, the public are advised to not drink the water, enter the water, allow their pets to enter the water, carry out any boating or other on-water activities, or eat fish from the lake 

Lake Rotoroa is currently at Alert level 

This means you should not drink the water, enter the water, allow pets to enter the water, carry out any boating or other on-water activities, or eat fish from the lake.

Water quality monitoring

In January 2025 new monitoring equipment was installed at Lake Rotoroa to provide real time data and insights into the condition of the water. The new equipment consists of a lake level sensor, weather station and two monitoring buoys that record dissolved oxygen and temperature, Chlorophyll-a (algae), oxidation reduction potential, pH, conductivity and ambient air temperature.

Over time, the equipment will provide baseline data to help guide decision-making and evaluate future efforts to improve water quality.

The monitoring equipment does not replace the manual grab sampling for potential health risks, and its data is not used for this purpose.

You can view data from the new monitoring equipment here. 

Things you can do to help

There are some simple things everyone can do to help improve the water quality at Lake Rotoroa. This includes: 

• Don’t feed bread to the ducks: As well as contributing to algae growth in the water, bread can make ducks ill as it doesn’t contain the right nutrition or calories that they need to keep warm in winter. Good alternatives are cracked corn, birdseed, pumpkin seeds or halved grapes, which contain the right nutrients to keep them healthy.  
• Pick up rubbish: By placing any rubbish you see in a bin, it helps prevent it from entering and polluting the water. 
• Report anything unusual: If you notice anything unusual in the lake including discolouration or odours, please report it to us on 07 838 6699.