I'm a homeowner, and have been reading about ground source heat pumps. Can an existing domestic water well be used to supply an open loop system? Here's the results of our well test last year, at the end of a dry summer when water tables are presumably lowest:

Well depth: 450 ft
Water level at start: 16ft
Sustained pumping level: 108 ft
Drawdown: 92 ft
Test pumping duration: 120 minutes
Average yield for pumping duration: 8 gallons / minute
Storage tank: 5000 gallons

Don't have a load calculation for the house yet, but the existing (oversized) propane furnace produces 120k btus. The site is in Northern California. Does this sound promising? Assuming I return the water with an injection well, are open loop systems considered environmentally friendly?