TOMORROW'S Our Water Our Land Our Future rally in Bowral is shaping up to be a major event of statewide, if not national, significance.

More than 1000 people are expected to attend to hear from a range of speakers about the impacts of coal mining and coal seam gas (CSG)?mining on communities and the environment.

The event has been organised by the Southern Highland Coal Action Group.

Convener Peter Martin said mining was the biggest threat the Southern Highlands had faced.

"Obviously, what is happening locally is important but this issue's much bigger than just the Southern Highlands," he said.

"This rally is about what's happening across Australia and is the biggest social issue in the country.

"Our governments are not doing their job; they're asleep at the wheel.

"They're not looking seriously at the impacts. They really, in a sense, have tried to close their eyes because they're all concerned about boosting their budgets."

Hume Coal, a mining project jointly owned by Cockatoo Coal and Korean steel maker POSCO, has an exploration lease covering land from Belanglo State Forest to Exeter, including Sutton Forest, where Mr Martin owns a property.

Hume Coal recently acquired a property in Sutton Forest from NewBall, which is part-owned by ad-man and Liberal Party stalwart Michael Ball.

A $1 shelf company set up by Cockatoo Coal and POSCO in September, named Aurelius Rural, conducted the purchase. Mr Ball claimed he did not know there was a connection.

Hume Coal was invited to attend the rally was but not invited to speak.

"If they're there they might get asked a couple of questions, but we are not going to give them a platform," Mr Martin said.

"They have plenty of opportunities to hold open meetings themselves, which they haven't done.

"You've got to ask yourself why a major Korean steel company, which says it cares about its reputation, starts buying properties through shelf companies in the dead of night.

"These are global players. They don't care about Australia, they care about their own steel-making processes and energy requirements in Korea and we are kidding ourselves if we think they care about what happens here."

Speakers featuring at the rally include broadcaster Alan Jones, Senator Bill Heffernan, Drew Hutton (Lock the Gate), Jeremy Buckingham (Deputy Chair of Upper House Inquiry into CSG), Bob Hunter (former Supreme Court Judge), Tim Duddy (Caroona Coal Action Group), Kathy Roche (local landowner), Goulburn MP Pru Goward and deputy mayor Larry Whipper.

The rally begins from 11am at Corbett Gardens and will be moved into Bowral Memorial Hall if it rains.