The Environment Protection Authority (EPA) has warned an accidental spill of the pesticides Orthene and Spin on a macadamia farm at Federal could affect water in nearby Whian Creek and Coopers Creek..
People have been warned not to pump or drink the water until further testing is complete and Rous Water has switched off pumps in the Wilsons River downstream of the spill.
Byron Shire Council has informed affected residents adjoining Whian Creek and Coopers Creek.
An EPA spokesperson said a large quantity of the pesticide mix spilled into an unnamed creek following tractor accident on a private property on Monday afternoon.
Around 2pm, a tractor was towing a trailer carrying a tank of pesticide mix when the connector failed, causing it to break away from the tractor and career down an embankment, crashing onto the creek bank.
The spokesperson said much of the 2,000 litres of the pesticide and water mix, which was being sprayed on macadamias, gathered in a natural pool in the creek and was later pumped out by the pesticides contractor.
Both the EPA and NSW Fire and Rescue attended the incident and took samples of the water.
NSW Fire and Rescue also built a weir further downstream of the creek to contain the spill, which was also pumped out.
The EPA estimates around 40,000 litres of affected water has been pumped from the two pools.
Orthene is an organophosphate and is toxic to aquatic organisms, birds and mammals.
Fire and Rescue NSW officers said they observed sick and dead fish in the natural pool where the pesticide mix had collected.
Rous Water is conducting tests on water downstream and has isolated the pumps in Wilsons River, which it says will not be pumping water until analysis confirms that the water is free of pesticides.
EPA director north Gary Davey said the spill was quickly contained and the risk of significant contamination downstream is unlikely. But the EPA recommeds that residents suspend their use of the water in Byrangery Creek until the sampling results are known.