Lake Tuggeranong research trial

Research officer recording data in a boat on a lake

The Institute for Applied Ecology at the University of Canberra is conducting research in Lake Tuggeranong to identify in-lake treatments that could improve water quality and reduce the number of closures caused by blue-green algae.

Tuggeranong’s urban water filter

Lake Tuggeranong was created in 1987 as an attractive focal point for the new satellite town, a place for recreation, play, exercise and conservation. But it also has another critical role—to filter and clean the water flowing from Tuggeranong’s suburbs into the Murrumbidgee River.

Urban run-off is generally high in litter, organic matter, harmful nutrients and other pollutants and, after 30 years, the lake is literally overloaded. As a result, it is frequently closed to recreational use because of toxic blue-green algae outbreaks.

It is an ongoing challenge to manage Lake Tuggeranong so it can fulfil the recreational needs of the community while also protecting water quality downstream in the Murrumbidgee River. At the moment, the lake doesn’t appear to be performing either role effectively. Something has to be done.

What we know (and what we don’t)

Lake Tuggeranong is often closed for primary contact, generally because of algal blooms. In the 10 years to 2017, the lake was closed for an average of 93 days each year.

There are some gaps in our understanding of how and why blue-green algae forms in lakes. Key factors that can influence an outbreak include high nutrient levels (both phosphorus and nitrogen, but phosphorus is likely to be the most important of these), longer days and warm temperatures (which explains why lake closures generally occur in summer months), and stratification (warmer water on the top, colder water on the bottom).

Lake Tuggeranong appears to provide ideal conditions for algal blooms. Of all the factors listed above, nutrient load offers the best opportunity to change those conditions. Understanding where the nutrients come from and how they behave in the lake is the first step in determining what interventions will work best to improve water quality and reduce the frequency and severity of algal blooms.

The research project

The research is divided into two phases.

Phase 1

Automated equipment, installed in the lake and also in the streams that flow into the lake, is already collecting samples to measure pollutant loads, oxygen and water temperature. Researchers also collect weekly manual samples of the water and sediment in the lake.

All these samples are analysed at the University of Canberra by the research team at the Institute for Applied Ecology.

Phase 2

Once the results from phase 1 are known, a series of trials will be conducted in the lake to test the most promising treatment options.

The Lake Tuggeranong Research Trial is jointly funded by the Australian and ACT governments as part of the ACT Healthy Waterways Project. The research is being carried out by the Institute for Applied Ecology at the University of Canberra.