Western Australian authorities are taking a peek at the state’s ancient underground waterways with the help of a giant magnet.

The magnet will be towed around by a helicopter as part of a $1.9 million investigation of groundwater to supply towns, miners and farmers in Western Australia's Mid West.

The airborne electro-magnetic survey is being funded by WA’s Royalties for Regions money.

It will cover 57,000 square kilometres of the East Murchison region.

The magnet can find ancient waterways – known as ‘paleo channels’ - up to 250 metres deep.

“At the end of the project we intend to have a three-dimensional picture of these ancient buried river systems both where they are and how deep they are,” Scott Macaulay, a senior hydro-geologist with the Department of Water, told the ABC.

“[It will show] the different sediments that make it up and different sands and clays and the different water qualities and the water table. It's very exciting.”

WA Water Minister Mia Davies said there was big demand in the Murchison mineral province, but low supplies.

She said the study could find new opportunities for growth in regional industries.

The project will last between six and nine weeks.