Randy,
No irrigation was added, although I have views slightly different from you. The last photos were taken in October 2004, during the Copa Los Andes (the South American team competition). At that time of the year, it rains a lot and the course is naturally green. But don't get fooled by the images. You never ever get a nice lie in the Old Course of MPGC. Fairway grass is still fescue and even with a lot of water it is totally different from bermuda.
Regarding irrigation, we've had times of terrible droughts (3 months without a drop), with very high temperatures (40 degrees celsius). And this in the high season when all the members that live far away go for vacation. You end up playing on concrete. I don't want the course to become a grass cushion, but at least it needs some grass, not rock. Irrigation should be used only scarcely, in these extreme situations. You may answer that we should accept those conditions, but when that means that 100% of the time that you use the club in the entire year or during 2 years, you have to play under those conditions, believe me: it's not nice at all.
As you may remember, MPGC is a very special club full of difficult members (I'm one of those). Most of us pay full membership and use the club 15 days a year at the most.