Contamination of farm dam water supply is an immediate threat after bushfire, warns Department of Primary Industries Soils and Water Team Leader Bruce Radford. "Large amounts of ash, sediment and debris can be washed into dams after rain resulting in unusable water supplies," Mr Radford said. Farmers in fire affected areas need to act now, before significant rains, to ensure they protect their water supplies. Farmers also need to take steps to protect water supplies from runoff out of stock containment areas. Mr Radford advises that contamination of water supply by ash, sediment and organic matter does not generally pose a health risk to stock. However, stock often refuse to drink the contaminated water. High volumes of sediment entering dams will reduce the storage capacity of the dam. Large amounts of organic matter, e.g. dung, can result in algal blooms, deoxygenation of the water and water becoming unusable.