I would agree with using aerated well water to get your trout pond to a less stressful temp., this is just a WAG but from my experience with supplying my pond with stream water I think about 5 GPM of cold well water to your small pond could make a reasonable difference, and split the flow to the pond with a separation of at least 30 ft. to allow a larger area of cooler water.
It's really something you would have to experiment with.
