Mr Ryan said Melbourne Water had gone to the extraordinary length of threatening criminal contempt proceedings against a member of his staff to suppress the documents being sought through Freedom of Information (FOI).

It is understood the documents predict the allocation of water savings from the Goulburn Murray Food Bowl modernisation project that will be available to supply Melbourne.

Mr Ryan's demands follow recent reports in The Age newspaper that senior government water officials have admitted the north-south pipeline will not deliver the previously guaranteed amounts.

It suggests that only 10 gigalitres, not 75GL, will be available in 2011.

"The Brumby Government must end this charade and come clean on exactly what water savings will be available," Mr Ryan said.

"If Mr Brumby has nothing to hide, then why won't he release the documents?

"It appears the government has not told the truth and, as we have argued all along, there simply isn’t enough water available in the Goulburn River to pump to Melbourne."

Mr Ryan lodged the first FOI request in April 2008 seeking documents on the proposed entitlement Melbourne Water will hold to water supplied to the north-south pipeline from the Goulburn River.

"After considerable delays and stalling tactics, Melbourne Water threatened criminal contempt proceedings against a staff member in my office because of the spurious reason that my staff member had acted inappropriately by providing me with information from the first FOI request," Mr Ryan said

"These threats were made despite the fact my staff member had submitted the first FOI request on my behalf and on my official letterhead.

"The situation is even worse since the government withdrew the threat when legal representatives acting on my behalf pressed Melbourne Water to justify its stance.

"It is a disgrace that the government is prepared to resort to threatening baseless legal action to protect documents that every Victorian has a right to see."