The energy/water/climate nexus in action: Lake Mead

Lake Mead’s Water Level Plunges as 11-Year Drought Lingers:

Lake Mead, the enormous reservoir of Colorado River water that hydrates Arizona, Nevada, California and northern Mexico, is receding to a level not seen since it was first being filled in the 1930s, stoking existential fears about water supply in the parched Southwest.

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In the 75 years since the workers began to hold back the Colorado River behind the Hoover Dam, the lake’s water has taken two precipitous plunges: first during the prolonged drought of the 1950s, which ranks second only to the current dry spell, and again in the mid-1960s, when water managers began filling Mead’s cousin 250 miles upstream, Lake Powell.

Neither dip was as severe or prolonged as that of the past decade. Nearly full in 1999, Mead has shrunken to 40 percent capacity, causing the ominous, bleach-white bathtub ring on the surrounding mountainsides to grow taller by the year. In the past five months, the lake steadily shed another 15 feet, to about 1,087 feet above sea level today. Four more feet and the lake surface will hit what would be the lowest mark since 1937 — something the government projects will happen in October.

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Mead’s disappearing act highlights the Southwest’s chronic overuse of Colorado River water. Trouble originated with the 1922 Colorado River Compact, which estimated the river’s water flow at 16.4 million acre-feet per year and divided that up among seven states and Mexico. Today, scientists believe the compact overestimated the flow by as much as 2 million to 3 million acre-feet, because flow measurements taken during the 20th century were skewed — it was the wettest century of the last 500 to 1,200 years, according to recent paleoclimate studies of tree rings.

Climate change threatens to stretch the river’s water even further. Over the last decade, the Southwest has suffered the sharpest temperature increase on the continent, declining late-season snowpack, loss of vegetation and rampant wildfires — all while growing faster than any other region in the United States. Eight studies completed from 1991 to 2007 predict that climate change will reduce the snowpack runoff that feeds the Colorado River anywhere from 6 percent to 45 percent over the next half-century.

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“We need to be making major policy changes to Western water,” Udall said. “And a lot of people aren’t willing to do it until you have a full-fledged crisis on your hands.”

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Greater cutbacks and impacts follow as Mead’s surface plunges further. When the 28.5-million-acre-foot reservoir’s surface hits 1,050 feet, or about 26 percent capacity, deliveries get slashed by 417,000 acre-feet, Las Vegas shuts down one of its two intakes and Hoover Dam’s massive turbines lose the hydraulic pressure needed to generate electricity. The maximum cutback of 500,000 acre-feet kicks in when Mead’s surface hits 1,025 feet, or about 20 percent capacity.

Even holding back the maximum 500,000 acre-feet of water — enough to serve 2 million residents for a year — accounts for less than a third of the reservoir’s current deficit, which is expected to grow as temperatures increase an estimated 2 to 4 degrees Celsius by 2050, as studies predict.

It’s hard to find a more immediate large-scale example of the energy/water/climate nexus in action than the US Southwest and the Colorado River. Rising temps, rising population, reduced water input, and potentially reduced hydroelectric generation, with a steaming pile of political gridlock and inadequate action thrown in for good measure.

A few more specific observations:

The article above also details some other, pricey, steps that are being taken to ensure that Las Vegas, which gets 90% of its water from Lake Powell, won’t run out of water. This is one of those utterly boring yet terrifying aspects of our energy and climate challenges: Even in those cases where we can “fix” a situation to alleviate the impacts through mitigation or adaptation, it can be very expensive. Similar to the peak oil situation, which is not a case so much of running out of oil (at first) as it is one of running out of cheap oil, we’re entering an age when many things we implicitly assumed would “always be cheap”, like water and basic food supplies (ask anyone counting on this year’s Russian wheat harvest), are about to become much more expensive. Tat will likely be true even in those cases where we take the right steps once we get around to recognizing and responding to the problems.

In a way, the worst thing about the Colorado River situation is that it will teach us the wrong lesson. I’d guess that Las Vegas won’t run dry any time soon, although we might have to spend billions to keep those taps flowing. The problem here is that we’ll see what happens here — wait for a growing mess to turn into a true emergency before acting and then save ourselves with a big, heroic effort — and assume we can apply that to other situations, like climate change in general. As I’ve pointed out so many times that frequent readers of this site must be spontaneously bleeding from the eyes at the merest mention of it, climate change is an extremely perverse situation because of the timing involved. A significant portion of the CO2 we emit tends to hang around in the atmosphere essentially forever, in human terms. It’s not something we can throttle up and down more or less at will, but a ratchet that goes up quickly (thanks to our current emissions rate) or at a more moderate rate (under any emissions rate one can reasonably expect us to achieve), but barring any technological miracle it will continue to rise throughout the lifetime of everyone reading this.

That’s still not the perverse part, though. The impacts that CO2 creates on human beings don’t appear instantly; many of them, like unfortunate shifts in water availability and sea level rise, take from years to multiple decades to creep into our consciousness, even though we’re continually adding to the atmosphere’s CO2 level during that time lag. And let us not forget those nasty feedbacks triggered by the warming from our CO2 emissions, such as the albedo flip in the Arctic from shrinking ice cover and everyone’s two favorite monsters under the bed, methane hydrate deposits and the already defrosting permafrost. Oh yeah — and there’s ocean acidification and the 40% die off of phytoplankton in the last 50 years. Got a good solution for either of those in a spreadsheet sitting in your desktop folder?

My point here is not to retrace the hall of horrors we’ve constructed for ourselves, but to point out that a business as usual approach to problem solving once we’ve recognized the danger is just as bad as the BAU practices in our economics and industrial processes and politics that helped create the mess in the first place. We’ll probably avoid a disaster in the Colorado River basin through the semi-panicked spending of large sums of money and possibly a little luck, but I fear that experience will only reinforce the wrong mindset for dealing with the problems of the next few decades to centuries.