I look at the current flow first, then I map out the pressure points. If the river’s swell is small, a modest dam is enough – a thin wall that stops a splash but still lets the stream move. When the water’s a storm, I’ll build a thicker wall, but I always leave a spillway. The trick is not to let the barrier become a barrier to everything else. I set the line where my own energy is threatened, not where others would rather it be. That way I keep my own course, and I can still see the rest of the river flowing freely.