Erosion in the Rio Puerco
Downstream effects of erosion
Sand and silt from the Rio Puerco and from the Rio Grande itself naturally build up (aggrade) the channel of the Rio Grande and form levees along the river margins. Spring floods occur when the snowpack melts in the southern Rocky Mountains; in natural conditions these floods breach natural levees and disperse water across the desert, where it evaporates and filters into the soil. Elephant Butte Reservoir, 100 km downstream on the Rio Grande near Truth or Consequences, NM, was built to catch Spring runoff water for later delivery to the lower Rio Grande basin in New Mexico, Texas, and Mexico.
The Corps of Engineers and the Bureau of Reclamation have built and maintained a conveyance channel, at substantial public expense, to ensure the maximum delivery of water into Elephant Butte Reservoir.
With or without a conveyance channel, sediment moves downstream with water. For several decades after Elephant Butte Dam was completed, in 1916, large quantities of sediment were carried into the reservoir, reducing its storage volume. Much of this sediment originated in the Rio Puerco. The diminishing output of sediment from the Rio Puerco is evident in slower filling of Elephant Butte Reservoir since the 1930's.