Veronica,
The swim meet was in Palm Desert http://www.desertseniorgames.org/, although this was not a USA Masters meet I have been told that USAMS have meets all over the USA. You have to join USAMS to compete but you do not have to work out with a masters team.
It's a good week for events in the desert. The Desert Senior Games had a 5k and a 10k on Sat 2/6 then the swim meet on Sun 2/7 and in Palm Springs the Tour de Palm Springs is on Sat 2/13 and the Palm Springs Half Marathon is on 2/14. Sadly I have to work so I can't participate in the Palm Springs events so am currently shopping for another half marathon.