A start to reduce water shortage, page-9

Yes, generally what you say about Werribee and the wetlands is correct.

Additionally huge gigalitres are released into Port Phillip Bay.

Obviously there is a cost to pump uphill through the north-south pipeline.
But it must be part of the solution.

Melbourne harvests all its water from Regional Victoria
with never a thought they are hogging Victorian State resources

and never a thought the water can be reused in irrigating fruit trees, wheat,
and even environment water.