Blue-green algae (cyanobacteria) are a type of microscopic, algae-like bacteria which inhabit most aquatic systems including streams, lakes, estuaries and the sea. There are many different species (toxic and non-toxic) and hot sunny days, increased nutrient levels and still weather conditions can provide optimal conditions for them to flourish – rapid growth can create a ‘bloom’ on the water’s surface. Blooms mostly occur in warmer weather (spring, summer and early autumn), but they can happen any time if conditions are favourable.
Blue-green algae can affect water quality, however we have treatment processes in place to ensure the continuous provision of safe and reliable water. Sometimes higher levels of blue-green algae can create an ‘earthy’ taste or odour in treated water, but the water remains safe to drink – we’ll always let you know if that changes.
All drinking water supplied to customers meets the Safe Drinking Water Act 2003 and the Australian Drinking Water Guidelines. We continually monitor and assess the water quality, and samples are regularly sent to an independent laboratory for testing. We also work closely with Goulburn-Murray Water, which manages a number of waterways from which we source water.
Blue-green algae in the Yarrawonga Weir in 2020.
Current blue-green algae detections
Blue-green algae has recently been detected in Lake Nillahcootie and in the Broken River system. The regional algae alert has been extended by Goulburn Murray Water to include the Broken River to Sheppartn, as well as the Broken Creek from Caseys Weir to Katamatite.
Goulburn Valley Water's water treatment processes are effective at removing the blue-green algae and thier metabolites, and we continue to monitor the raw water conditions.
There is currently no risk to our drinking water supplies from the expansion of the algae alert and Shepparton’s town water remains safe. This is also the case for Nathalia’s drinking water supply from the Broken Creek. Katamatite and Numurkah water treatment plants' raw water is sourced from the Murray Valley Irrigation District and is unaffected by the alert.
More information can be found at Goulburn-Murray Water's website.
Regulated (non-potable) supplies
Goulburn Valley Water supplies several towns with non-potable (non-drinking) water supplies. We recommend these customers have an alternate supply of drinking water.
Potable (fully treated) supplies
We regularly monitor for blue-green algae in our raw water supplies. Our water treatment plants remove algae and dissolved compounds as part of the treatment process before the water reaches your taps.
FAQs - blue-green algae and water treatment
The majority of our raw water is sourced from the Goulburn and Murray Rivers, their associated tributaries, and irrigation channel systems managed by Goulburn-Murray Water. In recent years, water storages on both the Goulburn and Murray River systems have experienced blooms of blue-green algae that have impacted on the water quality.