AUSTRALIA'S largest lake and the rivers that feed it are facing their most serious threats in decades, an advocacy group says.

The future of the Lake Eyre Basin is being discussed by the Australian Floodplain Association at a conference in western Queensland today.

Graziers, scientists and indigenous groups are meeting in Longreach to work out a plan to protect the lake and the rivers of the Channel Country from the rapid expansion of mining in the region.

AFA president Terry Korn says the meeting was prompted by the Queensland government's decision to rewrite laws protecting the Georgina and Diamantina rivers, which feed into the lake.

He also says concerns have increased over a government proposal to increase large scale irrigation in the region.

"The Channel Country rivers and the vast Lake Eyre Basin now faces their most serious threats in two decades," Mr Korn said in a statement.