Powell and Watersheds in the 21st Century

John Wesley Powell, the 19th century explorer, scientist and visionary who first tried to map and explain the West’s water resources, famously argued that government jurisdictions should be established based on watershed boundaries.

He was ignored on this point (as he was on others). But I’ve been playing recently with an argument that elaborates on this theme – that we’ve in a sense expanded the boundaries in the West of what counts as a “watershed” enormously, at least in the context of way Powell was thinking of it – a geographically bounded space based on a common water supply.

Stockton water writer Alex Breitler noted the connections last week in a comment on dropping levels at Lake Mead.

Here in the West, that space now runs from the Colorado River Basin east, across the continental divide, to include the front range communities and places like Albuquerque supplied by inter-basin transfers. To the west, it reaches across the Imperial Valley farm district to Southern California, which is then interconnected via pumping from the Sacramento Delta to the major watersheds of Northern California.

Here’s Breitler, with a nice map to aid your thinking:

Southern California water districts, including Metropolitan which serves LA and San Diego, rely on the Colorado River for a portion of their supply.

Notice the California Aqueduct, also feeding So Cal. That water is pumped out of the Delta near Tracy.

So… if Colorado River storage on Lake Mead dries up, well…

“That means they’ll want to pull more water out of the Delta,” San Joaquin County water resources coordinator Mel Lytle said at a meeting this week.


  1. Powell defined a watershed as “that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community.”

    That definition does NOT include artificial connections to other watersheds… which is why there is no water “community” in the West.

    Source: http://water.epa.gov/type/watersheds/whatis.cfm

  2. David –

    I realize that Powell’s definition does not explicitly apply here. But his underlying logic, regarding communities inextricably linked by a common water system, seems relevant today in a world of artificial rivers in a way that he could not have contemplated.

  3. I like to jokingly say that the Colorado River and the Sierra Nevada are both part of San Diego’s watershed. Some of the living things inextricably linked to that water system are the native birds living in the willows and mulefat at the center-right of this photo:

    Those willows didn’t exist before the mesas above were developed and people began watering their lawns, providing a year-round flow. (Urban runoff increased too, of course.)

  4. Pingback: “the largest artificial watershed in the world” : jfleck at inkstain

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