Farmer must pump his 'quota' of water all over his property, regardless if he needs it or not. Because if he uses less, his 'quota' for next term will be reduced.
So you have a list of Farmers all along the Murray-Darling, making sure they use their 'full' quota of water up. The system is being drained at full capacity always, every term, every year.
That's why the South Australians are bordering on violence when the subject of their 'trickle' comes to discussion.
Word of advice: DO NOT bring up the issue of Water Irrigation in a South Australian Pub.

CANALS OF MARS
This is a Topic I brought up in the Forum many many years ago.
Having also been given a private personal tour of the Riverina Irrigation set up by the Chairman of Irrigation out there.
There is no other way - but to introduce a sophisticated 'network' of WATERWAYS to retain, conserve, preserve, attain and transfer Water around the interior of Australia.
It's time to 'create' the mythical
INLAND SEA
from a mirage to a miracle!
Example: It rains heavily around the Coffs Harbour Region often - and instead of 20 metres of fresh rain water flowing out to sea, it is captured by the towns, and rural waterways and 'transported' inland via Canals and Pipes.
I've sat down at the Table with Sydney Water long ago.
They all shake their heads at the Sydney system that allows Megalitres of Storm Water to waste out at sea.
Even the Monsoonal Northern Territory has room to maneuver its wet season to other parts of the continent via Pipe and Canal.
The South Americans used mini-Canal systems to irrigate their massive (drug) Crops (made them very paranoid of raven haired men with pale skin and very shiny silvery armour).
Romans transported Water via Aquaducts.
Basically, the POLITICIANS can only do so much.
Well, they only take a political avenue of enterprise.
Australia is so lazy.
It does nothing to help itself.
Cries poor downtrodden convict all the time for another hand-out.
It's about time, Australia takes 'PERSONAL RESPONSIBILITY' and supports itself.
Construction of a continental system of intricate and at times, massive - network of irrigation Canals and Containment Lakes will not only improve the Australian interior water situation, but it will also 'moisturise' the inland (via evaporation during the day) as 'dew' during the nights.
Before you know it - the interior of Australia will be as productive as the Nile Delta (and a few other such things around the world in 'deserts').
Stop fart arsing around with Political answers.
Politics is not an answer for everything.
If you seek a Political Answer for this, beyond just a stamp of approval.
All you will get is more 'paperwork', less water.
Before 1788. The Inland waterways of Australia were all 'crystal clear' freshwater.
Allowing farmers to have stock 'trample' the edges of all these waterways have destroyed the natural 'nurseries' of all the native fish... resulting in artificial 'Hatcheries' (like at Nerrandera) to put fish back into the waterways.
...if it FLOODS in one part of the country, then have 'Waterways' (Canals) to drain it and transport it to a part of the country that is in DROUGHT.
(Meerkat:
"Simples" 
)