Quick post: On the lifespan of dams

There's an interesting piece in today's Albuquerque Journal, by John Fleck, on the life and (eventual) death of dams - this one happens to be about Elephant Butte in southern New Mexico. The challenge for EB is keeping the Rio Grande channelized enough so that water eventually reaches the actual reservoir, instead of spreading out in a typical distributary delta like so many others that occur around the world, when a river meets ultimate base level (the sea). Here, it's the constant battle between slope, sediment supply, and the currents of the river that dictate where the river struggles to make it to the dead pool of the dam. And unlike the Nile or the Mississippi deltas that are slowly disappearing, this inland Rio Grande near-delta actually re-forms every year. Given the amount of sediment thrown from semi-arid mountain landforms, it's no surprise that flood and sediment control are a major concern. Throw in impervious cover, and you speed up the work that water can actually do in carrying sediment long distances in New Mexico.

Marc Reisner has already written a scathing condemnation of the era of big dam building in the western United States, so this post won't add anything others don't already know. I simply find it a good reminder to remember that dams, like we mere mortals, also have a lifespan. I'll post another picture, here, of one of Santa Fe's "dead dams" as a reminder of this fact. In the game of rock-paper-scissors for dams, sediment always eventually wins over still fresh-water. Happy Valentine's Day.

(first photo, USFS, via John Fleck)