By Rusty Childress | Rio Verde
Every Arizonan has seen the headlines: “Colorado River can’t meet demand.” “Experts call for more cutbacks.” The stories sound serious — but they stop short of telling the truth that matters most.
If Lake Mead falls just a few dozen feet lower, the Central Arizona Project (CAP) — the canal that delivers Colorado River water to Phoenix, Tucson and Pinal County farms — won’t face “reductions.” It will shut down.
That’s not politics. It’s physics.
Lake Mead sits behind Hoover Dam, the upstream gate for the Lower Colorado River. When the lake’s surface drops below roughly 895 feet, Hoover’s outlet tunnels rise above the waterline. At that point, gravity — the force that moves every drop to Arizona — stops working. The canal runs dry.
Engineers call this “dead pool.” It’s the moment the Colorado River ceases to function as a delivery system. No policy, negotiation, or compact can make water flow uphill.
If Hoover reaches dead pool, Phoenix and Tucson lose about half their imported supply. Power generation at Hoover stops, taking 2,000 megawatts off the grid. Reservoirs downstream stagnate. Fish die. The delta in Mexico disappears.
Yet most coverage softens the crisis with words like shortage, cutbacks and resilience. The truth is simpler: without enough head at Hoover Dam, there is no CAP.
Some promise desalination or new pipelines will save us. But none exist today — and none can replace gravity.
It’s time for plain language. The Colorado River isn’t just over-allocated. It’s dying. And if we keep avoiding the word “collapse,” Arizona will be unprepared when the taps run dry.
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