|Jonathan P. Thompson|
We’ve got good news and bad news to report regarding the big aridification of the West this week. Let’s start with the good: After a two-year hiatus, the monsoon has returned to much of the Southwest, bringing huge rains with it. Tucson’s arroyos are running full and the Sonoran desert is getting positively lush. Multiple highways in Western Colorado were closed due to debris flows and flash floods. And a lot of farmers, especially those who lost ditch water early, are breathing a huge sigh of relief as, we suspect, are their crops.
The monsoon days are the best time of year in the desert Southwest. They always start out clear and hot and the mercury can shoot up into the triple digits before the cobalt clouds arrive, piled miles high in the sky. The first big raindrops bring the petrichor—the scent of blood and iron—followed by the deluge, followed by muddy water crashing through arroyos that were bone-dry just a moment earlier. Then the rain subsides, always just before sunset it seems, leaving the air crisp and clean. And the sun bursts through the clouds, setting the sky ablaze.
J. C y r @AllophileSabino Canyon is flowing again after last night’s storm; closed beyond the 1.5mi point… #azwx #getintotheoutthere July 24th 20218 LikesTomas Dawson @myfjcruiserWhen you realize the flooding is massive. #gatewaycolorado #flashflood #flood July 25th 2021
But all of that moisture falling from the sky isn’t enough to bust the drought, yet, nor can it save Lake Powell, which dropped this weekend to its lowest level since 1969 (when it was still filling up). Lake Powell’s growing bathtub ring is a visual indicator not only of the lake’s level, but also of the aridity of much of the West.
Powell’s downward slide began in 1999, falling 140 feet in just six years and bottomed out—for the time being—during the spring of 2005, before a substantial runoff that year bounced levels back up. But even the huge water year of 2011 was not enough for a full recovery. In the decade since, the level has crashed by 100 feet, in spite of healthy snowfall in 2019, bringing the lake to where it is now: The dam’s hydropower generating capacity is diminished, boat-ramps are rendered unusable, and the Bureau of Reclamation is desperately trying to shore up levels by releasing extra water from upstream reservoirs.
But the worst part of it all is what the shrinkage says about the health of the Upper Colorado River Watershed: it isn’t so good. And it will take more than one good monsoon to bring it back.
Bureau of Reclamation @usbrIn the next few days, Lake Powell’s elevation will drop below the record low of 3,555.10 feet reached in April 2005. These record low numbers stress the need for actions started last week under the Upper Basin Drought Response Operations Agreement.