We had considered going geothermal, and looked into using the pond as part of it. We were told that isn’t a good idea unless the pond was considerably larger and deeper than ours at 1/2 acre and averages 10ft when it is low in the summer.

Part of the problem is the efficiency drops in the later summer when the water temp is high, the cold bottom water is quickly lost as the loop heats it. Additionally, your pond water temp will offer no cool water refuge for fish when that happens. In the winter, ice can accumulate on the coils and lift them unless weighted, and the ice reduces efficiency.

In our case it was a double why bother, as it was too expensive to add to an old house with no vents, and the ground coil length needed didn’t even reach the pond. 1000’ from house to water. So I’m still dealing with fire wood and window AC, while occasionally playing the lottery.

Boy am I sick of fire wood.