The issue is not related to climate change, but a series of water policies that have favoured farming / agriculture over the environment / community use. In short, too much water being taken upstream.
As an Australian, it baffles me that we're trying to grow cotton and rice in the desert. I personally don't believe that farmers who make poor business decisions should be consistently bailed out by the government. I'd rather we pay for research into drought resistant crops, growing the right produce in the right climates, and failing that, retraining farmers and agri workers into new industries like solar. Lots of sun, not much water.