While the Government won't reveal what's on the agenda, it's believed the inter-governmental agreement (IGA) which will detail the operation of the $12 billion national plan for water security between the States and the Federal Government will be a high priority, with leaders expected to tie up more than four months of negotiations on technical issues with responsibilities and liabilities.

The National Farmers' Federation was briefed on the IGA so far on Monday, with outstanding issues to be dealt with at the meeting including a final agreement on new reserves for South Australia, how to move into contingency planning and the final shape of the Murray Darling Basin Authority.

NFF water spokesman Laurie Arthur said he would not be able to comment on the IGA until the final agreement is made tomorrow because he did not know which way the decisions would go on those outstanding issues.

Mr Arthur said while there would be some discussion too about the current crisis situation in the system, particularly the lower half of the Murray Darling Basin, he was unsure what more could be done by irrigators to help save the Lower Lakes and Coorong in South Australia because there were currently zero allocation for even high security irrigators in the Murray and Murrumbidgee valleys.

"I know some papers have been pointing the finger at the evil irrigator and there are a lot of myths about how they're going to fix the lower lakes, but there's not even any water for irrigation," Mr Arthur said.

"Unless governments want to give up water supposed to be for critical needs of towns, or take the very little carryover left to keep permanent plantings alive, I'm not sure where they're going to find this extra water for the Lower Lakes.

"There just hasn't been any run-off. It's the bleakest it's been."