"No new dams" is purely a political decision that could be reversed. As I said earlier there are conservation measures that were not explored, in particular storm water harvesting. Most of Melbourne's rainwater continues to wash out to sea... why? Why not consider minor council-run storages for things like parks and gardens instead of watering those areas from an expensive desal plant? Why wasn't that even considered? Why go for the most expensive and energy-intensive option as a first line of defence? Even with our huge population growth and 'houses growing like weeds' I'm sure we could have managed the next drought period with a couple of smaller dams and more intensive rainwater capture programs.No, 'no new dams' is a physical consideration. Knowing a couple of people in the business, and over the odd beer, I was told there are virtually no other catchments for domestic water in Victoria that can be exploited, without causing other apparently unacceptable issues.
Telling Melbourne residents "don't worry about it, you can hose your driveway down again, we've got the world's biggest desal plant" is not a good conservation message. As a country resident, I'm sure you can appreciate the need to conserve water even during our relatively wet years as the last few have been; to me the desal plant reinforced the bad message that "Melbourne people don't have to worry about drought, we've spent our way out of that problem".
And if you think the Desal Plant was expensive, try costing the idea of collecting storm water and re-processing it.
Mind you, the Desal Plant was made vastly more expensive because of the sweetheart deals the Labor government cut with the unions to get it built.