No, I did mean to say dam, unfortunately it is critically needed. The other solutions are either difficult to sell; people don't like to drink recycled sewage and although they claim to be interested in conservation, they'd just quietly rather drink rain water and let a few animals they'll probably never see in the flesh go extinct, or, they are too expensive, such as desalination plants or long distance pipelines. If you ignore the horrific environmental damage it would cause, the dam is probably the best option for the area's water supply. We might not be getting much rain by historical standards, but rain will always fall. Look at how much water is flowing along the Brisbane river at the moment and into the ocean. It's all being "wasted".
Ideally we'd have a doubled water system, with high quality drinking water to be used where it is needed, and lower quality water for other things. Ideally we'd be catching a lot more of the water that falls on the city itself, rather than having it run off our roof tops and roads and into drains which flow into the ocean. Ideally... well, a lot of things would be different. There are many solutions to the water problem without building the dam, either expensive or unappealing. Obviously in this case, the environmental impact of building a dam is just too severe to warrant it being built, but unfortunately I can't see an easy solution. I am realistic enough to understand that there are times when we need to allow a few species to go extinct in the name of 'progress', but this is one of the cases where we would be better off evacuating half of the city than killing the species in question (obviously that is a solution which is impossible to sell to the population). Whatever the alternative is, we just can't let this dam go ahead, but what is your proposed solution to the water issue?
What this issue boils down to is convincing the government (which involves convincing the wider community in order to convince the government that it will be a popular opinion) that the Mary River catchment is important enough to warrant spending extra money and/or drinking recycled water to avoid destroying it. Part of that will be identifying the best alternative water solution.
Also, it seems that most people just can't understand why these species are particularly important. Educating the public in this respect is probably almost impossible as most won't be able to properly grasp the concept of biodiversity (most will forever say "each species is equally important, isn't it?" and probably find it offensive if you suggest otherwise).
Perhaps another tact which would help is pointing out the people who will lose their homes and businesses. While I sympathise with those people, the reality is that the species are important enough to make them irrelevant, but perhaps not so in the eyes of the government and wider community.
