I can't tell if the dam is any higher now. Since the spillover looks like it's in the exact same spot, I'd guess that it isn't. But I examined the pond upstream a little and found that there is another spot, tucked under the bank, where there is a cluster of bark-stripped saplings under the surface. So I'm wondering if the beavers built the one-foot dam so that the water would be just deep enough to cover the entrance to this den, but don't need for it to get any higher. Hmm.
Then Bhikku and I examined the other side of the bank. Because of the width of the creek and barbed wire fences that still line the creek in most spots (remnants of the land's cow-pasture days), we had to go the long way: out to the road, over the bridge, down the other road, through the pasture gate and tall grass. When did come to the other side of the beaver pond, we discovered the source of the critters' construction materials. They have a ready supply in the form of a cluster of young autumn olive trees that have come up in that spot over the last few years. I think most people hate these nuisance trees because they're invasive, but to me they look better than bare pasture and they also have a nice silvery underleaf that's attractive. The beavers seem to like them, too, and I have no problem with sacrificing these trees that grow back practically overnight anyway. We also found the spot where the beavers pull the downed branches under the barbed wire. They must make a lot of noise when they're wrestling those trees down to the pond.