bobminer - you say [In Perth our rainfall from the average in the 70s has dropped at an alarming rate,] What has actually happened bobminer is that in the 1970's Perth region rainfall changed from a high rain regime pre 1970's to a lower rain regime after that. Here is a rain chart for this lower rain post 1970's period built from 3 stations intended to measure average rain each May to Oct period that fell across Perth dam catchments. The average of 39 years is 912.6mm bobminer - hardly statistics that warranted the Labor Govt elected 2001 to panic into seawater desalination. They could have easily improved catchment runoff by trimming some catchment bush - but were terrified of the Greens response to any touching of the bush. So Perth has been saddled with huge ongoing seawater deasal costs now for ever more. Mad. When you take in the truth conveyed from this chart - consider what Perth Govt water has spent over the decade publicising their wacko slogans - "our drying climate" and "independent of rainfall" etc. But it is worse than that because the fact of Perth adopting seawater desal acted as a trojan horse assisting the even more groundless and vastly more expensive takeup of seawater desal in the eastern States. In my opinion mike68 has it pretty dam correct.
