Update: It is a muskrat. Ralph said that he thinks it has chewed
thru the liner and that is why the water is so muddy. The frozen
ground is why we haven't had water loss. He is going to the farm
store to see if they have traps. Hopefully they will tell him the
best way to catch the critter.
It looks like we may have to redo the goldfish pond this Spring. The
upper pond still has a thick layer of ice and there is no way to keep
the goldfish and orfe till then. I feel sick...