Innovative algal monitoring at Lake Burragorang

Science improving our understanding of source water quality

Our science research team has been investigating innovative water quality monitoring options, including algal fluorescence sensors and satellite imagery, to better understand potential water quality risks from algal occurrences in Lake Burragorang.

Algae are a natural feature of aquatic environments, and most algae are harmless, except some types of cyanobacteria.

Commonly referred to as blue-green algae, cyanobacteria are photosynthetic bacteria that live in water and can produce toxins that can be a risk to livestock and cause public health issues for humans. The only way to tell if algae are harmful is to take a sample and analyse it in a laboratory.

“Lake Burragorang stores about 80 percent of Sydney's water, so improving our understanding of source water quality helps guide our operations and reduce the risk of harmful contaminant exposure,” WaterNSW Water Quality Scientist, Liz Symes, said.

“These water quality monitoring projects will enable WaterNSW to ensure that all possible data sources are leveraged in calibrating our Integrated Water Quality Model, vital for making high quality predictions of water quality.”

Warragamba Dam wall and lake
Lake Burragorang, which is the water stored by Warragamba Dam, holds approximately 2,000 gigalitres - about four times more water than Sydney Harbour.
Lake Burragorang aerial
Water that fills Lake Burragorang drains from a catchment area of over 9000 square kilometres that stretches from south of Goulburn to north of Lithgow.

Satellite remote sensing and unmanned aerial technology

In partnership with UNSW researchers, WaterNSW has embarked on a two-year project that uses satellite imagery and unmanned aerial vehicle (UAV) technology.

The project, in collaboration CSIRO, SA Water and Water Research Australia, uses a drone to collect ultra-high spatial resolution imagery of algal occurrence events in Lake Burragorang.

“The images assist researchers to understand seasonal patterns of algal occurrence across the lake and help identify contributors to algal spread,” WaterNSW Water Quality Modelling Manager, Marlène van der Sterren, said.

“One of the advantages of UAV imagery is the ability to capture high resolution imagery and use hyperspectral cameras to support the identification of cyanobacteria to genus level. This is vital for making more accurate predictions of water quality, allowing for better decision making in managing water for the Greater Sydney area.

"The outcomes of this project will enable WaterNSW to ensure that all possible data sources are leveraged in calibrating the Integrated Water Quality Model,” Marlène said.

VPS senor on lake
Total algal sensors were installed on Vertical Profiling Systems in Lake Burragorang in 2020. The sensors measure the fluorescence signal predominantly associated with chlorophyl-a, which is an indicator of algal growth.
Lake Burragorang aerial
The Warragamba Special Area protects 260,880 hectares of the catchment of Lake Burragorang which supplies 80% of Greater Sydney’s water.

Algal sensors installed on real-time lake monitoring stations

Total algal sensors were installed on real-time lake monitoring stations in Lake Burragorang in 2020. These sensors measure the fluorescence signal predominantly associated with chlorophyl-a, which is an indicator of algal growth.

“The project supports our Integrated Water Quality model because the high frequency data helps to explain the spatial and temporal dynamics of phytoplankton populations,” WaterNSW Water Quality Scientist, Liz Symes, said.

“The benefit of sensors is that they continuously measure and send updated results, as opposed to grab samples that require staff to go out on a boat to manually collect samples, which is not cost effective on a high frequency basis and can create a lag in knowing whether there is an algal event developing.

“The results have found that the sensors performed well and should continue to be deployed as an early warning system, with future work likely to see data incorporated within our Integrated Water Quality Model to reflect a multi-variable and multi-dimensional system,” Liz said.

algae sensor locations
Locations in Lake Burragorang where total algal sensors are deployed (above left). Plot of derived fluorescent chlorophyll (top right). Bar plot of grab samples for the corresponding period (bottom right).

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In the flow

Published date: 15 August 2023

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