I see at least three issues, and they may not be issues, but worth mentioning. Depending on the amount of well water, percentage wise, used to fill the pond, could significantly affect the temperature as well water is generally much colder than surface water. Well water is also generally low in dissolved oxygen, and can have a high carbon dioxide content making it acidic. Shooting the water into the air can release much of the carbon dioxide and increase the oxygen, but it can, in low humidity areas add to the cooling effect, like swamp coolers. The other that comes to mind is the exit pump, which needs some form of screen with low enough suction to prevent the fish from being sucked in and pressures damaging the fish.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard