Routine monitoring by State Water and the Department of Water and Energy detected high numbers of potentially toxic blue-green algae in Burrendong and Windamere Dams.

A red-level warning indicates that waters are unsuitable for recreational use or primary contact by domestic users and may also pose a threat to livestock.

The species of blue-green algae identified are potentially toxic and may cause gastroenteritis in humans if consumed and skin and eye irritations after contact. Boiling the water does not inactivate algal toxins.

Algal blooms can develop in a 24-hour period and can spread rapidly along the river.

Local residents and visitors should avoid any water that appears bright green, where obvious green scums are present, or a distinctive odour is noticeable.

Blue-green algae are usually very obvious, appearing as clumps or specs in the water and are often associated with a strong musty or earthy odour.

People are advised not to enter the water, not to drink untreated water or bathe in water drawn from the river while a red level warning is in place.

Landholders are advised to remove stock from the river foreshores as blue-green algae are known to cause stock illness or even death.

Dogs are particularly susceptible as they ingest algae by licking their coats.

People should not eat mussels or crayfish from red-level warning areas. Any fish caught should be cleaned and washed thoroughly in uncontaminated water and any internal organs disposed of before consumption.

This red-level warning will remain in place until the Central West Regional Algal Coordinating Committee advises that it has been lifted.

The Department of Water and Energy and local councils will continue routine water quality monitoring of Burrendong and Windamere Dams.

Information updates about blue-green algae blooms and red-level warning areas can be obtained from the Regional Algal Coordinating Committee - freecall Algal Information Hotline on 1800 999 457.