Earlier this spring I predicted 2025 would be the year of children building forts. Though time may yet prove me correct, the early signs are not promising. Despite a flurry of activity, with ambitious plans for palatial forest hideouts and streamside bunkers, there is currently little in the way of actual fort structures beyond some desultory sticks leaned against a rocky outcrop. The problem isn’t boredom with the idea of building things, it’s just that the focus has shifted. All the energy that I thought would be going to hideouts has instead been directed to the even more timeless activity of damming the stream.
If ever there was a stream made for damming, the one that runs through the middle of the farm must be it. It carries a substantial but not overwhelming amount of water. Some prior owner straightened out the section that passes closest to the farmyard, which led to it creating a high-banked channel with a bottom of solid rock. The erosion this entailed is unfortunate (erosion Ed has since stopped with the profligate planting of willows) but the high banks and hard floor provide natural parameters for a dam.
The appeal of building dams is not so different from the appeal of building forts. In both cases small humans use the materials at hand to improvise a structure that makes a temporary imprint on the world. The appeal of dams is that the change is so visual and success or failure so obvious. If the dam impounds water, it is a success. If not, it needs more work.
I’ve also been pleased to see that the basic technique of building a dam is so intuitive as to be universal, at least when concrete and heavy machinery are not involved. Large rocks make up the structure but do little to impede the stream, since the gaps between them hardly slow the water. Smaller rocks partially plug these holes, which holds the water back a little. Finally, something like mud or leaves or clay completes the seal.
A moment ago I said that dams are temporary, and no doubt this spring’s projects will prove to be in the longer run, but I’ve been surprised by the robustness of the two the kids have really committed to building. Both survived a series of intense thunderstorms with only minor damage.
The rush of water that accompanies heavy rain demonstrates some interesting dynamics about streams when it hits an obstruction. Intuitively, it would seem like a dam would mostly make a pool behind it by raising the water level, and this does occur. But each flood deposits a remarkable amount of gravel, meaning the pool rapidly fills in. With a smaller stream like ours, for a pool to persist for any length of time it actually needs to be below a ledge or obstruction tall enough to make a little waterfall. Over time the falling water will dig a pool, and when the stream floods, instead of depositing gravel the turbulence pushes it through the pool and out.
I don’t think either of the dams have a sharp enough drop to make this happen, and even if they did, the process takes time, and dams made of stone and clay don’t last forever. But anything involving cool water is worth doing on a hot, sunny day.