This month, 50 tonnes of phoslock slurry ” a clay nanomaterial that immobilises phosphorus ” will be sprayed on the surface of the water.
Swan River Trust drainage nutrient intervention manager Peter Adkins said more than 70 tonnes of nitrogen and 10 tonnes of phosphorus flowed into the Swan River from the Ellen Brook area each year.
‘Phoslock has been successfully used in the Canning River for over 10 years and is a safe nutrient binding solution,’ he said.
‘Binding the phosphate essentially breaks the food cycle for algae by reducing nutrients in the water so the project will focus on reducing nutrient export from the Ellen Brook catchment.’
Mr Adkins said the next phase of the $2 million Ellen Brook Wetland Project would be building a series of off-stream wetlands.
He said some water from the Ellen Brook would divert to the wetlands to improve water quality before re-entering the brook and flowing to the Swan River.
Ellen Brook Integrated Catchment Group executive officer Rosanna Hindmarsh said the project would ‘reduce nutrients entering the upper Swan River to prevent algal bloom’.
‘Ellen Brook contributed the highest load of phosphorus and nitrogen to the upper Swan River, which kills fish, particularly when it’s warm and there’s low oxygen in the river,’ she said.