Like many conspiracy theorists he has some good points.
The use of huge amounts of water for cotton farming and other purposes has certainly had a huge effect on the inland river systems. The Darling river, Australia's longest river, was navigable as far as Bourke in the 1800s. One could not even imagine it today. Other than having been deprived of a considerable amount of water the river is contaminated by fertiliser and pesticide run off (extensive aerial crop dusting is used on cotton), and the introduction of carp has wreaked havoc on the river ecosystem and caused the loss of native fish species. All in all a colossal case of mismanagement.
Unfortunately he confuses mismanagement and greed with conspiracy.