So we would gather up all of the washed up scrap wood, and we would engineer these dams to block off certain streams. Sometimes we would leave gaps in the wood to allow small fish and minnows to get through, then we'd block them off, effectively trapping the wildlife on one side. Other times we would completely dam up a creek, and watch as the water level quickly rose up and above the sides of the channel. I'm still not sure why we did this, other than to say we could.
I only bring this up, because it's the sort of thing that was going through my head when I decided to tackle the wildly growing tree in front of our house.