I've been monitoring the water that I pump from a natural spring under my house into my 1/2 acre pond and have found that it is about 60 gallons per hour unless its been raining. Currently the water empties into the pond about a foot below the surface and the water from the spring is 59 degrees. Assuming the spring water stays roughly that temperature throughout the Summer, I'm wondering whether it would be better to run a length of PVC into the bottom of the pond to inject the new water into the bottom of the pond. Which would be most likely to reduce the possibility of stratification?

This is a low pressure, intermittent release from a sump pump, right?

Right. Very low pressure, just enough of a pump to get it out of the basement then its gravity to the pond. The pump runs every 6 minutes and moves 5 to 6 gallons per time on a dry day. Lots more water during a rain storm.

That rules out using a horizontal aeration sprayer, I think.

I would aerate the water (see Cecil's methods) before having it enter the pond at the top of the water column. My guess is mixing 60 deg water with the warm surface layer is the best approach.

It will be interesting (e.g. a learning experience) when someone with actual experience, a proper education, or the correct physics for this problem corrects me.