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With a 'megadrought' forecast to hit the US in the coming decades, parched states are turning to increasingly radical solutions to fill their reservoirs.

Arizona is leading the way with plans to create artificial rain clouds by flying planes over the Rockies and seeding the sky with silver iodide.

They hope the technology will allow them to mitigate some of the worst impacts of climate change – but not everyone is convinced.

With a 'megadrought' forecast to hit the US in the coming decades, parched states are turning to increasingly radical solutions to fill their reservoirs. Arizona is leading the way with plans to create artificial rain clouds by flying planes over the Rockies, and seeding the sky with silver iodide

The process of cloud seeding was first proposed in the 1940s at the General Electric labs in Schenectady, New York.

Two decades later, the Central Arizona Project and the Salt River Project invested in research to make it a reality.

'It hasn't been taken off the table as a potential tool as we work our way through drought now and in the future,' Nancy Selover, Arizona's state climatologist told Becky Brisley at Cronkite News.

Since 2007, CAP has put about $1 million toward research happening in other states to increase the supply of water in the Colorado River system.

Water in the air, even in dry areas, can be transformed into ice crystals by using planes to seed the atmosphere with chemicals such as silver iodide or dry ice

The system works on the premise that rainfall takes place when supercooled droplets of water form ice crystals.

As a result they become too heavy to remain suspended in the air, and fall, often melting on their way down to form rain.

Water in the air, even in dry areas, can be transformed into ice crystals by seeding the atmosphere with chemicals such as silver iodide or dry ice.

They create rain by inducing nucleation – a process in which water is in the air condenses around the particles and crystallises to form ice.

But some scientists are concerned about silver building up in river basins, as well as legal uncertainties over who should get the additional water.

Compared to other alternatives, such as desalinating seawater, cloud seeding is the cheapest option, though it isn't going to be a drought-buster on its own.

In a recent Wyoming Weather Modification pilot project, the technology resulted in an increase of seasonal snow water accumulations of 5 to 15 per cent.

But Selover, the state climatologist, told Cronkite News that the trickiest part of cloud seeding is measuring whether an area got more rainfall.

'So the effectiveness of it is in doubt,' she said. 'It's not that it's completely ineffective – they're pretty sure it has some impact – but it's pretty hard to measure.'

Some scientists are concerned about silver building up in river basins, as well as legal uncertainties over who should get the additional water. Pictured is Lake Powell, near Page, Arizona