The marine parks encompass almost half a million hectares north-east of the town of Derby, in the Kimberley. (Supplied/AAP)

The marine parks encompass almost half a million hectares north-east of the town of Derby, in the Kimberley. (Supplied/AAP) Source: Supplied/AAP

The joint management of Western Australia's Horizontal Falls by Traditional Owners and the state government is being hailed by conservation groups as a milestone.

The creation of the Lalang-garram Horizontal Falls and North Lalang-garram marine parks, which together cover more than 460,000 hectares, were announced by the Dambimangari Traditional Owners and the government on Wednesday.

Chairman Francis Woolagoodja told the ABC, "it's exciting for us as the Dambinmangari Traditional Owners, and it's also exciting for WA.

"For us it's a role that we can play monitoring and preserving our area. The second part is identifying that these areas are well known around the world and it's putting WA on the map," Mr Woolagoodja said.

Map of exemption area for exploration and mining around Horizontal Falls.

Source: Supplied/AAP

Kimberley campaign manager for Pew Charitable Trusts Tim Nicol said Indigenous rangers would use traditional knowledge and modern science to protect the area.

"Protecting the Lalang-garram Horizontal Falls Marine Park is a major achievement and one step closer to the vision of a Great Kimberley marine park for the Kimberley coast," he said.

"A choice has been made to make long-term conservation a priority over short term profits for industry."

The decision is set to protect the falls Sir David Attenborough described as "one of the greatest natural wonders in the world", particularly as they were threatened with a copper mine in 2012.

Five marine parks have been established so far in the Kimberley.

Environment Minister Albert Jacob said the government had been working with Traditional Owners since 2013.

"The final management plan gives a high level of protection to all areas of the marine parks and an integrated approach for managing the whole of Dambimangari sea country," he said.

The parks will open up employment and economic opportunities for Dambimangari people, and would protect natural assets, such as coral reefs and marine species, including dugongs and turtles.