On my old land, had a big pond, I had a very bad beaver problem!!! I mean big! I was losing ten trees a day not joking! I had my trapper's lic, plus got a permint to kill any and all. Started out doing the same thing, tear down the dam a bit and pop one with the 22's, but, if luckie, get one or two in a night, next day 10 more tree's down, then you have wait for days again for them to come out in the light, they wait until total dark. Then more tree's down!! Then I did a big blizzt, I had two high banks on this big pond, had a buddie on high ridge, with a 12 gauge with buckshot, me in the catails in cheast waders with a full rifled 870 12 gauge with sabot's, I was getting eat'n alive by the bugs , even with a head net, then the fat rat pack came one by one, fixing the dam, we put out about 6 traps before this on all routes, when the big boys where on the dam, and light going, I let the lead fly!! took out four on the big dam, bud got two heading for the water! In the morning, 3 in the coni's. But, You will never win, if they have made a house, your toast, you can kill ever one of them, and next month you have a new tentant. They smell water miles away, when a family pod get to big for the water they have, they kick out the young one's and they will move in as soon as they smell water, or hear running water!
This went on for a whole spring to fall, I think I took out about 40 beavers intotal, lost well over 100 6 inch trees and about 30 24 inch trees. After the beaver war, my large pond,mini lake was toast for stocking trout!! Because of all the decay of the dead beavers in the hut, and never coming back up after being shot.