Australia generates a significant portion of its electricity from running water. Marcus Casey looks at how the system works.
In the heart of the Snowy Mountains, water tumbles through enormous turbines causing them to spin. This simple motion produces clean electricity powering homes up and down the east coast of Australia.
Behind the scenes it's much more complex, both in engineering and history. 
The Snowy Mountains hydroelectricity and irrigation complex began construction in 1949.
The scheme, regarded as one of the great engineering wonders of the modern world, consists of sixteen major dams, nine power stations; one pumping station; and 225 kilometres of tunnels, pipelines and aqueducts that were constructed between 1949 and 1974.
The current chief executive of Snowy Hydro Ltd, Paul Broad, has worked in the energy sector for more than 20 years. He's proud of the legacy and efficiency that has been achieved at the company.
Last financial year Snowy Hydro produced 4.7TWh of electricity. The hydroelectric station has one of the fastest capabilities in getting energy to the grid, taking just 90 seconds to generate power for sale.
"Water is the best storage of power in the world. We just open the floodgates and let the water go," Broad says.
"That storage of water is phenomenally valuable. The dams are what recharges the power - Mother Nature at work.
"We are the lucky country in many ways, and the Snowy Scheme is a key part of our lucky country."
Monitoring the system constantly and regularly undertaking upgrades can improve electricity output by up to 10 per cent.
"We have submarines in the tunnels to observe them, and they are in great shape," he says.
The scheme was originally meant to be an irrigation source of water for inland NSW and Victoria. Electricity generation was a byproduct and a means to pay for moving water from the east to the west. Channelling water to irrigators remains a major function of the scheme. Under licence, each year, Snowy Hydro releases an agreed amount of water downstream. The flow is regulated by the NSW government and takes into concern the rainfall, drought conditions and snow melts.
Taking water cycles into account, the system now irrigates most crops grown to the west of the Dividing Range. Dozens of agricultural industries rely on the water releases to produce healthy crops. Without Snowy there would be no Riverina rice industry.
When the revolutionary idea to use water for power began, it was envisaged that the system would be able to provide just enough power for Canberra. In fact, it's spread far more widely, sending clean, reliable and efficient electricity to NSW, Victoria, South Australia and even Queensland.
Hydro electricity is ingrained in the community, Broad says.
"It is unique. Water is precious to us all in the scheme of life, and the hydro industry is a fundamentally very different one to the traditional power industry.
"There is a deep connection between our operations and the wider community, and the scheme is an integral part of keeping the lights on in metropolitan and regional areas across NSW, and Victoria and some parts of Queensland."
Hydropower's green credentials are impeccable. Its environmental impact is closely monitored by government agencies and Snowy Hydro also employs its own environmental experts.
"We are the ultimate green power source, and there is no better renewable than hydro," Broad says.
"And the Snowy Scheme will be [an] integral part of the power industry for a long, long time."
The scheme is also drenched in multicultural history, made by migrants and European refugees. It's an example of how multiculturalism can work.
"We don't talk enough about Australian history these days, and we seem to move away from great achievements," he says.
"Europe was still war torn in 1949, and migrants who were bitterly against each other came together to work on a great engineering marvel. The workforce broke down all the orthodoxies, and put together a community with diverse cultural backgrounds.
"This job is more than doing a job. It is meant to be about the memory of these blokes who did the work, which has made all of this possible.
"They were a special generation. They came together in an experiment of multiculturalism, and you could not find a better one."
How water makes power
" Hydroelectricity is a system where water is used to generate energy
" Water from elevated dams is pumped through a system of tunnels
" Falling water is channelled through a series of turbines
" The pressure of the flowing water on turbine blades rotates a shaft which drives an electrical generator, converting the motion of the water into electrical energy
" The electricity generated is then pumped into the grid
" Hydropower is the most advanced and mature renewable energy technology
" More than 160 countries use some form of hydropower worldwide
" The world's largest hydropower station, China's Three Gorges Dam, can produce 98.8 billion kilowatt-hours of electricity, roughly equivalent to burning 49 million tonnes of coal.