Officials fear ‘complete doomsday scenario’ for drought-stricken #ColoradoRiver — The Washington Post #COriver #aridification #CRWUA2022

Click the link to read the article on The Washington Post website (Joshua Partlow). Here’s an excerpt:

The first sign of serious trouble for the drought-strickenAmerican Southwest could be a whirlpool. It could happen if the surface of Lake Powell, a man-made reservoir along the Colorado River that’s already a quarter of its former size, drops another 38 feet down the concrete face of the 710-footGlen Canyon Dam here. At that point, the surface would be approaching the tops of eightunderwater openings that allow river water to pass through the hydroelectric dam. The normally placid Lake Powell, the nation’s second-largest reservoir, could suddenly transform into something resembling a funnel, with water circling the openings,the dam’s operators say. If that happens,the massive turbines that generate electricity for 4.5 million people would have to shut down — after nearly 60 years of use —or risk destruction from air bubbles. The only outlet for Colorado River water from the damwould then be a set of smaller, deeper and rarely used bypass tubes with a far more limited ability to pass water downstream to the Grand Canyon and the cities and farms in Arizona, Nevada and California. Such an outcome — known as a “minimum power pool” — was once unfathomable here. Now, the federal government projects that day could come as soon as July.

The back of Glen Canyon Dam circa 1964, not long after the reservoir had begun filling up. Here the water level is above dead pool, meaning water can be released via the river outlets, but it is below minimum power pool, so water cannot yet enter the penstocks to generate electricity. Bureau of Reclamation photo.

Worse, officials warn, is the remote possibility of an even more catastrophic event. That is if the water level falls all the way to the lowest holes, so only small amounts could pass through the dam. Such a scenario — called “dead pool” — would transform Glen Canyon Dam from something that regulates an artery of national importance into a hulking concrete plug corking the Colorado River. Anxiety about such outcomes has worsened this year as a long-running drought has intensified in the Southwest. Reservoirs and groundwater supplies across the region have fallen dramatically, and states and cities have faced restrictions on water use amid dwindling supplies. The Colorado River, which serves roughly 1 in 10 Americans, is the region’s most important waterway.

On the way to such dire outcomes at Lake Powell — which federal officials have begun both planning for and working aggressively to avoid — scientists and dam operators say water temperatures in the Grand Canyon would hit a roller coaster, going frigid overnight and then heating up again, throwing the iconic ecosystem into turmoil. Lake Powell’s surface has already fallen 170 feet. Lucrative industries that attract visitors from around the world — the rainbow trout fishery above Lees Ferry, rafting trips through the Grand Canyon — would be threatened. And eventually the only water escaping to the Colorado River basin’s southern states and Mexico could be what flows into Lake Powell from the north and sloshes over the lip of the dam’s lowest holes.

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