Rowan Moore Gerety writes:

If it weren’t for the Colorado River, Albuquerque wouldn’t exist — at least, not as a city of half a million. Which is interesting, because the city itself is nowhere near the river: The Colorado and its tributaries flow on the opposite side of the Continental Divide from New Mexico’s largest city. The thing that joins the city to its water — the thing that allows Albuquerque to exist, it’s no exaggeration to say — is the Azotea Tunnel.

From a trio of small dams along Colorado tributaries — the tunnel openings are about as wide as a one-car garage — the Azotea Tunnel snakes beneath the mountains and high desert steppe of the Jicarilla Apache Nation in northwestern New Mexico, carrying water that will emerge 26 miles later and flow down a concrete sluice into a tributary of the Chama River. From there, the Chama carries water that would have ended up in the Pacific Ocean toward a city and a river system that drains ultimately into the Gulf of Mexico and the Atlantic Ocean beyond.

The American West is thick with similar geography-defying infrastructure; it’s how we’ve managed to spread the flow of a single river system to 40 million people across seven states and 350,000 square miles — more than half again as big as the original watershed. Los Angeles, Salt Lake City and Denver, too, all lie outside the Colorado River basin. Las Vegas and Phoenix, though within it, still rely on a vast assemblage of canals, pipelines and reservoirs to move and store water, a network of concrete and steel that took 100 years and untold billions of dollars to build. Still more nodes of this network divert water for agriculture, accounting for some two-thirds of the Colorado’s flow. [Continue reading…]