Community members are being cautioned to avoid all contact with the water at Lake Bullen Merri, including swimming and fishing.
The Department of Energy, Environment and Climate Action (DEECA) has advised a blue-green algae bloom is affecting the lake.
Blue-green algae can cause skin rashes and itchiness; irritation of the eyes, ears and nose; respiratory irritation; liver damage; and asthma-like symptoms.
Adjoining landowners and recreational users are advised to avoid all contact with the water and keep pets and livestock away until DEECA declares it safe.
Corangamite Shire Council Chief Executive Officer David Rae said the lake is not owned or managed by Council.
"Council is delegated to manage certain parts of the land around the lake but not the lake itself.
"Low levels of blue-green algae are always present in the lake and bloom in warmer weather."
There have been a number of options suggested to improve water quality at Lake Bullen Merri that have been investigated or implemented including:
- Topping up the lake to dilute the nutrients that feed the algae but there is no source big enough to make a difference in such a large lake.
- Redirection of small external catchments, such as Naroghid Road, is likely to add more pollutants including herbicides, pesticides, litter and heavy metals.
- Aeration systems have been tried but were ineffective and very expensive.
- In 2022-2023 an 18-month trial of an ultrasonic system to break up algae but, again, the size of the lake meant it was not enough to be effective.
Council's Lake Bullen Merri Management Plan, which includes details of responsible authorities, can be found at https://go.vic.gov.au/3Nt1eFf
