I think you have at least one more otter. Yes, beaver and otter co-exist in ponds. Otter have much larger home territory than beavers, so they might have several beaver colonies in their home range.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).