Answer: I think I can solve your mystery, but I'm not sure I can help you control it. I believe you have a mountain beaver living close by. These are rather primative animals, not related to beavers, but more resembling a large rodent. They are vegetarians and live mostly on native (or cultivated plants). They are hard to trap because they don't go for bait. If you can remove vegetation around your property they usually go away (they like the cover of plants). A dog will usually drive them out of a nesting spot in your yard. For more information, contact Washington State University Cooperative Extension; Whatcom County, 1000 N. Forest, Suite 201, Bellingham, WA, 98225-5594. The Extension Agent there can help.
Best wishes with your garden!
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