It is contained in a lengthy taxpayer-funded report to the ACT Planning and Land Authority in September last year and only now made public under Freedom of Information.

ActewAGL rejected the Hume site just three days after the move was recommended in the report by international professional services company GHD.

Although the draft study circulated among government agencies for comment, it has not been raised in the Assembly's estimates committee hearings.

The Hume Industrial Planning Study said the site should be used for a purpose that generated more employment.

It said the gas-fired power station and data centre would be a low-employment generator and recommended the Government consider reserving the land for medium to heavy, and employment-related, industrial purposes.

Days after it was finalised, ActewAGL wrote to the Government nominating a site at Hume, but closer to the residents of Macarthur, saving more than $30 million and leaving vacant a site worth at least $50 million.

In the ensuing furore, ActewAGL scaled down its proposed power station and data centre from $2billion to $1 billion.

Commissioned last year by ACTPLA, the study which cost $43,000 said Fyshwick was accommodating higher-order industrial/retail uses, which suggested its location for warehouse and large-scale industrial development might no longer be economically viable.

While expansion of Hume for large-scale industrial uses was preferred, the report warned Hume's potential to supply future industrial land should not be overestimated because it could be absorbed rapidly by large land-takers, such as the proposed gas-fired power station and data centre. ActewAGL's preferred site, Block 1610, was not suitable for industrial development, according to the study.

The block's southern boundary abutted a ridgeline, which could be used to protect residential areas from industrial development impacts.

''This ridgeline has some potential for the creation of an improved wildlife corridor between the residential and industrial land uses,'' the report said.

GHD is designing Actew's $300 million bulk water security program.

Compiled by a range of experts, the report presents three concept plans, with the power station in Hume, but does not nominate a specific alternative site.

GHD approved the report for issue on August 13 last year and issued it in September.

ActewAGL's chief executive, John Mackay, who wrote to Chief Minister Jon Stanhope to say Tuggeranong was the preferred site, said he was unfamiliar with the report, although he would have been surprised if his project team had not seen it.

''There is no doubt at all we had discussions with the Land Development Agency on many occasions and at some [meetings] where I was at, where they talked about this planning study, and they had different ideas and all the rest of it,'' Mr Mackay said.

''But as far as I am concerned, in a formal sense, the Hume site was never taken off the table. I can tell you, at the time we decided, we had a clear belief that all three sites were available.''

A spokeswoman for Mr Stanhope said the GHD report had not been presented to the Government.

It had been finalised a month after ActewAGL selected its site, the spokeswoman said.

ACTPLA's chief executive, Neil Savery, said the report had been superseded by the Eastern Broadacre Study, which stretched from the Federal Highway, Majura, to Hume and the southern broadacre area.

The study was still being completed and would then go out for public consultation.

He said Actew, because of its infrastructure role, and other government agencies were consulted for the GHD study.