So we are at the A/C thread, huh? Let's try this...
I've used watercooled A/C's almost exclusively for several years. My assumption is you will have access to flowing water (not a frozen pond) all year around.
Option 1.)
A normal A/C that is simply cooled by water. Here is a company that does nothing but this:
http://www.miamihp.com/products.html aka water cooled A/C.
Option 2.)
Water cooled air handlers, like deacon said:
Chillking makes water cooled air handlers. I guess u would just be circulating the water constantly from the pond and then back in. What's the average temp of ur pond water? Im sure if the intake is towards the bottom, you'd have a pretty consistant temp year round. My guess would be to check with Hydro Innovations and go from there. Good luck!
For option 1, you would run pipes to and from the pond. You would use a pump (probably some sort of well pump to put the water to the A/C unit and then return it to the pump (probably far from the water intake pipe) This is so common that a lot of illegal indoor grows use there swimming pool instead of 1.5 million gallon pond, so you should be good to cool many tons of A/C.
On a normal A/C the compressor sits outside "and gets cooled" by the air moved on a large fan... that would be the outdoor unit, with the water cooled A/C's there is no outdoor unit. The compressor "gets cooled" by the water you are running from the pond.
In option two, you run the concept of a radiator. The water from the pond gets pumped the same way as in option 1, but t goes to something that resembles a radiator. Fans would blow air through the "radiator" which is really an air handler and cools the air as it travels through it. The benefit of option 2 is that the electric consumption is MUCH less. You are not running a compressor, but rather a pump and some fans. IT works best when the water is really cold and does not work as good if the water is anywhere near warm.
Unless you like departing with your money, stay away from Chillking. Every major manufacturer makes water cooled units. In one way shape or form water cooling is used on a LOT of commercial building in the world. Chillking market the horticulture market and hence charges for the niche.