My goldfish pond is about 1 foot deep and about 4-5 feet wide, holds about 150 gallons. What can I do about keeping the water temperature high enough to keep the fish from hibernating?

What you do depends pretty much on how cold it gets where you are. The bottom line is the water temperature. If your climate is harsh enough to get your water temperature consistantly below 50 degrees, your goldfish will go semi-dormant. Since your pond is small and shallow, a trough heater such as is used by farmers to keep water unfrozen for cattle and horses might work, but will be very expensive to run. They suck up electricity. If you get winters like we do here in Chicago, your pond will freeze solid. It might be a good idea to bring your goldfish indoors into a large, well-filtered aquarium tank. Goldfish do fine in aquariums. Koi are very difficult to keep healthy in these conditions. In any case, your best friend during the winter is a good pond thermometer.

(Answer courtesy Bob Passovoy)