In an Australian-first, innovative floating covers that have been shown to reduce evaporation by more than 70 per cent in Western Australian trials have been installed at three Water Corporation dams in southern agricultural areas this year.
At a cost of $2.8 million, the covers have been put on a 12,000 square metre dam at Ravensthorpe, 10,000m2 dam at Salmon Gums and a 6000m2 dam at Lake King.
This follows a 19-month trial of the recycled plastic covers on a 3000m2 dam at Wellstead that found evaporation could be cut by 73pc, or about a third of the dam's total volume, saving 1.6 million litres of drinking water.
Water Corporation Great Southern regional manager Adrian Stewart said the results were so positive, it has decided to extend the use of the covers to bigger dams this year.
He said this had involved the use of hundreds of thousands of modular, hexagonal discs - known as a HexaCover - that were an Australian invention and had not previously been used in Western Australia.
They were installed by majority Aboriginal-owned construction company, Benang, and will reduce the need for water carting - while also helping to protect water quality.
"The discs stay on permanently for 20-25 years and we will be measuring the effectiveness over their lifetime," Mr Stewart said.
"The discs are spread across the dam and shuffle together.
"They move with the wind and don't have to be secured.
"As the water level goes up and down, they spread out and resettle."
Mr Stewart said one of the big challenges of dam covers was to not stop rain and run-off coming into the dam.
But he said the HexaCover was flexible and allowed rainfall to enter the dam.
This year, the Water Corporation and The University of Western Australia will measure input of rainfall and output of drinking and agricultural water from the Ravensthorpe, Salmon Gums, Lake King and Wellstead dams to further refine evaporation losses.
Mr Stewart said annual rainfall across this southern region of WA had declined by about 20pc since the 1970s, with seasonal water carting needed in each community to secure drinking water in the face of increasingly unreliable rainfall.
He said stopping evaporation would lift dam capacity and reduce the need to cart water.
"It is all about having a more sustainable water supply in the regions," he said.
This project is being delivered by the Water Corporation and jointly funded by the Federal and WA governments as part of the $43.8 million Western Australia Connections package.
Australian Government funding is provided through the National Water Grid Fund (NWGF).
The NWGF aims to improve water access and security by delivering nationally important water infrastructure projects that unlock potential, build resilience and promote community growth and sustainability.
The WA Government, through the Water Corporation, has allocated more than $290m for new drinking water and wastewater projects in regional WA in 2023-24, including $43.4m for projects in the Great Southern.
WA Labor senator Glenn Sterle said the dam cover project would deliver secure and reliable water to communities right across WA.
"Projects like this that use innovative covers to minimise water evaporation mean we are protecting what is one of our most valuable and precious resources," Mr Sterle said.
"This is providing WA with resilience as we face a dry and changing climate."
WA Water Minister Simone McGurk said securing drinking water supplies was fundamental to the growth and development of climate-resilient communities across WA.
"Nowhere is need greater than in southern agricultural areas, where the impacts of climate change are more pronounced than anywhere in Australia," Ms McGurk said.
"This project, funded jointly by the State and Commonwealth governments, will significantly reduce evaporation and yield more drinking water from rainfall.
"Alone, this project will not eliminate the need for water carting, nor is it only answer to the supply challenges in the region.
"But it is one of a suite of measures the government is taking to ensure communities have secure, sustainable drinking water well into the future."
Agricultural Region MLC Shelley Payne is keep to see what impact covers would have at Ravensthorpe, Salmon Gums and Lake King.
"Rainfall is increasingly unreliable in the region, so it's fantastic to see innovative solutions being put into action that help protect valuable drinking water sources in the community," Ms Payne said.