HIGH levels of blue-green algae have been detected in both Waranga Basin and Lake Eppalock.
Goulburn-Murray Water has warned people to avoid contact with the water in Waranga Basin.
The basin will remain open but the authority recommends water users seek an alternative option. Pets should also avoid the water where possible.
The authority will position warning signs at major recreational areas around the site.
These will remain in place while high levels of blue-green algae are present.
A spokesperson said people could still sight-see and enjoy other activities at Waranga Basin that did not involve direct contact with the water.
GMW has issued similar advice for Lake Eppalock.
Signs of algae contact include skin rashes or itchiness; sore eyes, ears and nose; or, if swallowed, nausea or vomiting.
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The water authority recommended anyone who came in contact with the water should wash affected skin immediately in clean cold water.
It warned people should not use affected water for cooking, drinking, washing or showering and boiling the water would not make it safe.
The spokesperson said it was impossible to predict how long the algae would remain at high levels.
The water authority would continue to monitor the situation.
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