A quick Google on evaporative cooling turned up the following.
http://www.consumerenergycenter.org/...e_coolers.html

It states that evaporative cools in dry atmospher can cool the hot air
by as much as 30 degrees. The plus is that they use much less engery
that a AC unit.

It would seem one would need a evaporative cooler to chill air then an
air/water heat exchanger to cool the pond water. It sounds doable.

Up here in British Columbia I dont have to worry about the pond getting
too hot - especially with the summer we are having.

Courageous wrote:
A better solution would be to run the water through some aluminum radiator coils,
and to mist water over the radiator coils. Perhaps run a water line through the pond,=
before going to the sprinkler system, that would help, again minimally.


If those aluminum radiator coils were buried somewhere cool, you'd have a heat
exchanger, and it would be effective. The challenge will be that the ground
gets pretty hot in AZ in summer. So finding that cool spot will be work, and
the digging will be deep.

C//