I think it was John Howard who once described a conservative as someone who did not believe that everything his grandfather said was necessarily wrong!
Nobody could accuse present day water managers (bureaucrats and attention seeking scientific advocates)of being conservative. They appear to approach current issues from the clear position that their forebears didn't really have a clue about what they were doing.
So much so, we now have a widespread "conventional wisdom" view that in the Murray Darling Basin (MDB) our rivers are all "over allocated" and that this has given rise to their "ill-health".(They conveniently overlook the fact that the "ill-health" was really the natural result of extreme dryness which Mother Nature has dramatically corrected over recent days.)
The much maligned forebears of these modern "dark green" commentators recognised the massive variability of the inland rivers of temperate Australia and devised a dynamic, adaptive, self correcting management system. Water licenses/entitlements were issued subject to seasonal allocations. Think of it sequentially-it rains, or it doesn't. Our dams have plenty in storage or they don't. Our water managers then, guided by long debated Water Management Plans, determine the percentage (if any) of the licensed amount which may be extracted.
This methodology allows account to be taken of environmental and critical human needs before any extractions for irrigation are allowed. It means that in a year when water is in short supply such as in 2008/9 only 3,500GL were extracted in the MDB, not the 13,700GL upper limit which the Guide to the Murray Darling Basin Plan keeps referring to.
Farmers understand the system and its logic and accept the risks involved. They also recognise the smoke screen of politicians talking about granting certainty. A concept totally foreign to Australian farming!
Likewise, they recognise the nonsense of asking the CSIRO to calculate the Sustainable Diversion Limits for each of the rivers. If "sustainable" means the "annual" amount that can always be extracted, then given the fact that all of our inland rivers,including the mighty Murray, sometimes actually stop flowing, then the limit must be placed at nil.
Faced with these variability issues the modern water managers then revert to using averages. Given the massive spreads around the average such mathematics quickly becomes meaningless.
All of this was well understood by those who devised the system. It is clearly not understood by those who glibly state that our rivers are over-allocated and advocate correcting the perceived problem by having the Government buy up water licenses without ever mentioning the role of seasonal allocations.
Oh for more conservatives!