Robbing Peter to save Powell ~ The Land Desk

The Bureau of Reclamation is draining reservoirs to fill reservoirs 

Jonathan P. ThompsonJul 21

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Throw a few pesos to Thompson. He’s not some entitled white guy, but a creative and hard working journalist that loves his home in the South West. rŌbert

The Horseshoe Bend overlook, which affords some 50,000 selfie-snappers per month a gander of the Colorado River as it bends back on itself, is surely one of the most popular viewpoints in the Southwest. I’ve passed by it many a time, but have never been tempted to stop. Instead, I rev the engine on the ol’ Silver Bullet, drive into the western fringe of Page, past the McDonalds and the most-out-of-place golf course on the planet, and then take a left turn to get to my favorite viewpoint: The one that offers a stunning, explicit, full frontal look at Glen Canyon Dam. 

It gets me every time—an almost physical blow to the gut coupled with the insta-vertigo inflicted by confrontation with the sublime. 

I’m not sure what it is about the dam that invokes such a strong reaction. Perhaps it’s just the sheer size—700-feet high, 1,500 feet long at the crest, 300 feet thick at its base—or the ungodly amount of water it holds back. Maybe I’m mourning the hundreds of miles of Edenic canyons that were inundated. Maybe it’s a combination of terror and anticipation of the power that would be released if the dam finally cracked and crumbled. 

Or maybe it’s the hubris that the dam represents, the belief that, with enough concrete and engineering ingenuity, we humans could control that wild, tumultuous creature known as the Colorado River and harness it to turn thousands of miles of desert into lawns and alfalfa fields and golf courses and housing developments. Sure, it worked. Until it didn’t. And now Lake Powell’s water levels have taken a great fall, and all of Bureau of Rec’s engineering, and all of Bureau of Rec’s plumbing, can’t put Powell back again. 

Still, they’re trying. Last week the Bureau of Reclamation announced that they would crank open a few valves on the massive plumbing system known as the Upper Colorado River, releasing extra water from Flaming Gorge, Blue Mesa, and Navajo reservoirs in order to shore up the rapidly declining water levels in Lake Powell. 

The point of this exercise is not to keep houseboats from scraping bottom—which is already happening—but to preserve what remains of Glen Canyon Dam’s hydropower generating capacity. Already the dam has become less potent in this respect, because as water levels drop, so does the pressure the water exerts, meaning that the same amount of water run through the turbines generates less power. More worrisome is what happens when the level falls below 3,490 feet, or the minimum power pool: Generation stops altogether. 

That would mean that Glen Canyon Dam’s electricity output would plummet from 10,000 megawatt-hours or so of juice each day—enough to power some 350,000 homes—to near zero. That would be very bad for the Southwestern electricity grid, which is already strained by heat-induced soaring demand coupled with diminished hydropower generation across the West. Grid operators would have little choice but to turn to natural gas generation to fill the gap, increasing greenhouse gas emissions and electricity costs. 

In one month, from mid-June to mid-July, Lake Powell lost 416,000 acre feet of water—or 135 billion gallons (which translates to about five and a half feet of surface-level elevation). About 36,000 of those acre feet vanished via evaporation. The rest was sent through Glen Canyon Dam’s turbines, destined for the Grand Canyon and then shrinking Lake Mead. If levels continue to drop at that rate, the Lake will reach minimum power pool in a year from now (The Bureau of Reclamation is projecting a slower rate of decline, even in its worst case scenarios. See accompanying graph).

The feds know they can’t stop the drop with this scheme. But via the planned releases—totaling an additional 181,000 acre feet over the next six months—they can slow it down, theoretically. Instead of falling another 28 feet by the end of the year, the surface level should only drop by, wait for it, 25 feet, assuming a continuation of current rates of decline. Basically, the Bureau is draining down three reservoirs in order to offset evaporation from Lake Powell. 

It just might succeed, in delaying the inevitable. But without a lot of help from Mother Nature in the form of massive winter snowfall across the entire Upper Colorado River watershed, there is little chance that the planned plumbing adjustments will amount to much. And if the snows don’t come, what happens to the depleted upper basin reservoirs and the people who rely on them? 

The plan seems even crazier in light of a proposal to build a pipeline that would siphon yet more hydropower-generating water from Lake Powell and ship it to southwestern Utah, or plans to divert yet more water from the Colorado River Basin toward the urban centers of Colorado’s Front Range. But then, none of it is any crazier than building the dam in the first place with the belief that doing so would turn a desert into an oasis.

Lake Powell is just six inches away from hitting it’s lowest level since it was filled. The previous low record was set in 2005. 

2 thoughts on “Robbing Peter to save Powell ~ The Land Desk

  1. Hi Jerry, As you know I read just about every little bit of info about reservoirs that I can find or you find for me (like this) but this is the very first time I’ve seen someone refer to the upper basin in terms of evaporation:

    “Basically, the Bureau is draining down three reservoirs (in the Upper Basin – edit BG) in order to offset evaporation from Lake Powell. ”

    That should be a 3 inch headline somewhere.

    The 36,000 af estimate is about 8.6% of total drop of 416,000 af (hard to estimate, bathymetry always changing). That sounds suspiciously like an evaporation pan coefficient.


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