Here in PA not far from you the frost line is 28 inches--and this was a bad
winter. My pond is over 4ft deep and the same fish have been there since
1992.
I would make it deeper and add a air stone in the winter.

Pat

"news2.news.adelphia.net" wrote in
message ...
We built a pond in northern VA last year, about 15' x 22', 2 1/2 feet
deep.
Kept at least an opening in the pond through the winter but only 13 of the
17 goldfish survived the winter. No idea what happened to the 4 that
didn't
make it, didn't find any remains, etc. when we cleaned the pond a few
weeks
ago. Is this unusal for the first year, the fish range in size from about
1
1/2 inches to about 5 inches, the bigger ones are still with us? We had a
lot of string algae all through the winter so took that as a decent sign
that there was plenty of oxygen in the water, didn't feed the fish once
the
water dropped below about 55 degrees? Ideas.