What Exactly is a “Watershed” Any More

John Wesley Powell famously argued in the 19th century that the West’s political jurisdictions should be shaped around watersheds, rather than the often arbitrary rectangles that had been used to establish our governmental geometry as the nation moved across the great plains.

Azotea Tunnel beneath continental divide, Norther New Mexico, courtesy USBR

Azotea Tunnel beneath continental divide, Northern New Mexico, courtesy USBR

In an odd sort of way, we seem to be carrying out Powell’s wishes in reverse – using interbasin transfers to reshape watersheds to fit the boundaries of existing governmental jurisdictions.

Consider Colorado, where the water tends to be on the west slope of the Rockies and the people on the east. But what’s a mountain range when you’ve got modern engineering, as Chris Woodka explains:

The Continental Divide has been breached by ditches or tunnels a couple of dozen times throughout the state’s history, bringing over an average of nearly half a million acre-feet of water annually to the Front Range.

I’ve been thinking about this because because of a comment one of my water friends made suggesting that in some sense at this point you have to link vast areas of the west into a single giant watershed: Northern and Central California, thanks to the diversions to Southern California, which is linked via diversion to the Colorado River. In terms of diversions, Phoenix and Tucson are in some sense “downhill” from the Colorado thanks to the Central Arizona Project, as is Albuquerque via the San Juan-Chama diversion. And of course much of Colorado’s front range urban corridor, as Woodka explains.

Oddly, the one thing we might consider leaving out is the Colorado River Delta in Mexico, since no water actually gets there any more.

One Comment

  1. To make Northern California and Southern California into one big watershed might make sense to a water manager, but it ignores geography — specifically, the Tehachapi Mountains. Getting water from places like Shasta over the highest water lift in the world requires three separate power stations, no less, and uses an astonishing amount of the state’s total energy budget.

    Yes, we in California have made this work — sort of. But is more such massive geoengineering the answer? What about capturing local rainfall during storms, and holding it, instead of rushing it to the sea as rapidly as possible?

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