‘Toxic to humans and animals’: Red alert issued for Griffith’s Lake Wyangan

Griffith’s Lake Wyangan is once again under a red alert, meaning the water quality is so poor that people should not swim there, fishing is not recommended and pets should stay clear.

The local council last week inspected a water sample, which revealed the lake has high levels of blue-green algae – bacteria that can produce dangerous toxins.

“A red alert-level warning indicates that people should not undertake recreational activities where they may be coming into direct contact with the water such as swimming, as well as domestic uses including showering and washing,” the council said in a statement.

“Contact with the water may also pose a threat to livestock and pets. Warning signs are positioned at key recreational areas and will remain in place while high levels of blue-green algae are present.”

Water NSW says a red alert means the water may be “toxic to humans and animals” and could appear green with clumps of scum in it.

The State Government authority has also issued a toxic blue-green algae alert for the Lachlan River from the Lake Brewster outlet channel to Willandra Weir and for Lake Wetherall in Far West NSW.

Charles Sturt University environmental scientist Dr Xiaoying Liu says she’s not surprised by the recent algal blooms, given the hot weather across the Riverina and western NSW over December and in early January.

“The likelihood of the occurrence of algal blooms or hypoxic water [low dissolved oxygen concentration] events is increased if a large volume of organic matter has built up on the flood plain or water temperatures are high,” Dr Liu said.

“When the air temperature remains high for a while, the water temperature warms up as well.

“Recent storms that have swept across the region could wash off organic material to the waterways. Excessive organic material inputs can result in poor water quality through the development of algal blooms or hypoxic water events, resulting in very low dissolved oxygen concentrations in the waterways.

“Bacterial communities can respond to changes in organic matter source quite rapidly. Bacteria in the water become more active to break down the organic material during hot weather, consuming dissolved oxygen in the water. This means there might not be enough dissolved oxygen for the fish, which would increase the risk of fish stress or even fish kills.”

Dr Liu says water quality is a shared responsibility and government departments are working in partnership with scientists, water managers and communities to monitor the algal bloom in our waterways.

Government departments can release environmental water with good quality into waterways to dilute the water and improve its health.

“Environmental water is water allocated and managed to improve and restore degraded river, wetland, and floodplain ecosystems, including the plants and animals that depend on these ecosystems,” Dr Liu said.

However, she said climate change was also an important factor, with its impact making the management of river systems more challenging.

Griffith’s Lake Wyangan was once the heartbeat of the town and a focal point for family picnics and aquatic sports.

However, frequent algal blooms have meant the lake has been largely out of action for the past two decades.

Local wetlands expert Geoff Sainty previously devised a plan to fix Lake Wyangan by creating a natural wetland habitat on the eastern shore to offset the blue-green algae. However, his proposal was rejected by Griffith Council in 2019. Mr Sainty has since died.

At present, the council is advising Griffith residents to not enter the lake, drink untreated water or bathe in water drawn from the lake while this warning is in place.

Before consumption, any fish caught should be cleaned and washed thoroughly in uncontaminated water and any internal organs disposed of appropriately.

The red alert warning will be in place until further notice. The council says it will monitor the level of blue-green algae regularly and provide updates to the public and via its website.