The City of Ballarat has temporarily closed Lake Burrumbeet for all uses following the detection of a blue-green algal bloom at the lake.
Testing has confirmed the presence of toxic algae, which can pose serious health risks to people and animals.
Blue-green algae can affect the colour and taste of water. Some species of blue-green algae produce toxins that are harmful to humans and animals when they are consumed, inhaled or contact the skin.
As a precaution, all water-based activities, including swimming, wading, fishing and boating are prohibited until further notice.
Water affected by blue green algae can be unsuitable for drinking. No stock or pets should be allowed to make contact with or drink the water.
Warning signs advising the public that Lake Burrumbeet is closed to all activity have been installed at the lake at all boat ramps, park entrances and track entrances off Bo Peep Road. Additional signs have been installed along the north-east shore near the recreation reserve and caravan park.
The City of Ballarat will conduct regular visual inspections of the lake to observe any visible blooms, scum formation, evidence of dead fish and to check that warning signs remain in place.
Analysis of water samples from Lake Burrumbeet reveal the presence of Dolichospermum at a biovolume mass of 8.653 mm 3/L.
City of Ballarat Director Infrastructure and Environment Bridget Wetherall said public safety remains the highest priority.
"We understand this closure may inconvenience lake users but protecting the health of our community is paramount," she said.
"Blue-green algae can cause skin irritation, nausea, gastronintestinal, mild respiratory, such as hayfever-like symptoms, and other health concerns, so we urge people to follow the warnings and stay out of the water."
The City of Ballarat is in the process of contacting adjacent landowners in the Lake Burrumbeet area and will contact the managers of the Lake Burrumbeet Caravan Park, advise the Burrumbeet Ski and Boat Club, the Burrumbeet Racecourse and Recreation Reserve Committee and the Friends of Lake Burrumbeet of the lake's immediate closure.
The Department of Energy, Environment and Climate Action, Glenelg Hopkins Catchment Management Authority and Central Highlands Water have all been notified of the outbreak.
Blue-green algae is frequently caused when there are higher than normal temperatures and high pH readings in the water. In dry periods, low water storage levels and low inflows can also create similar problems.
Other contributing factors can be large amounts of nutrients (nitrogen/phosphorous) which have been building up on surrounding land during dry weather flow into a waterway during heavy rain.
The City of Ballarat will continue to monitor water quality at Lake Burrumbeet and provide updates as conditions change.
The closure will remain in place until test results confirm that it is safe to reopen.
