This dam was completed in 1916 as part of the Rio Grande Project by the federal Bureau of Reclamations. The 1902 Rio Grande Project allowed the Federal Government to build dams, reservoirs and canals in 16 arid and semi-arid western states including New Mexico. The vast scope of the Feds control of water in the west is complicated (but interesting) and beyond my ability to summarize it here.
The downstream side of the Dam - the Rio Grande reduced to a small stream.
The upstream side - The Elephant Butte Reservoir/Lake is at less than10% capacity. The Dam and the cliffs show where the water level has been in the past, as the reservoir has not been at full capacity since the late 1990's. The Marina below was dismantled when it ended up on dry land and rebuilt in its present location.