The Manilla River, downstream of Split Rock Dam has now been issued a red alert warning by Water New South Wales.
It comes less than a week after high levels of blue-green algae were found at Split Rock Dam.
With the red alert warning in place, people are advised not to consume the water or come in direct contact with it.
Farmers are also being warned it could pose a threat to livestock and pets.
Town water supplies remain safe to drink.
NOTE: VISION ONLY