Tom, Josh, Tim
From the little I know, Royal Adelaide uses street run-off which are cleansed through wetlands established at a cost of about $1.5M (partly funded by Government grants). The local EPA limits the transfer of this water to 200 ML annually, which equals the amount of water taken from the aquifer via bores. Annual rainfall is perhaps 14 inches - and less in some years.
A key short-term outcome of the aquifer has been a halving of the salinity levels, which is relly important as the irrigation season generally runs for 8 months. That used to mean a lot of salt sitting in the surface waiting a long time to be flushed out, eventually. Rain at Seaton (Royal Adelaide) is far more infrequent than in the Melbourne sandbelt, so the salt issue is significant.
A key long-term outcome of the aquifer is that it is less likely to be under stress, and will continue to be available to irrigate the course. Town water costs $3 per kilolitre (yikes).
Similar schemes are in place at The Grange Golf Club and at Glenelg Golf Club.
Whether or not Royal Adelaide is over-watered today is a matter of opinion and degree. However, I am quite confident in saying that it receives less irrigation per annum than equivalent courses in southern California.
James B