A little bit more on the ACT 40 gigalitre water cap which sort of explains some of the numbers. from the ABC news-
“Concerns have been raised that Canberra has been shortchanged with its Murray-Darling Basin water allocation of 40 gigalitres.
The cap was agreed to at a meeting of the Murray-Darling Basin Ministerial Council last week.
Water activist and microbiologist Peter Collignon says the deal is limiting.
He says currently with stage three restrictions the ACT uses about 50 gigalitres a year with 24 gigalitres being pumped back into waterways. That leaves a net consumption of 26 gigalites.”
http://www.abc.net.au/news/stories/2008/05/27/2256549.htm for the complete article.