The El Niño is an oceanic phenomenon relating to unusually warm waters in the Pacific Ocean. South American fishermen in the 1600’s, observing that this warming of ocean waters usually peaked in December, named it after the Christ child. This warming of a vast body of water has, of course, an effect on weather patterns around the globe.
The flip side of this phenomenon, La Niña, can have an opposite effect. In Arizona, we JUST LOVE the El Niño. It brings rain to the desert southwest and snow to our mountains. This results in great run-off to our in-state rivers and builds storage behind our dams. It can also bring heavy snow to the mountains of Colorado which results in higher levels to Lake Mead and Lake Powell along the Colorado River.
La Niña, however, is Arizona’s Red-headed Stepchild. It dumps rain on the Pacific Northwest, northern California (apparently Mother Nature always liked her best) and the northern Midwest, but leaves us bone dry. Did I mention that NOAA’s Climate Prediction Center, forecasts an 87 percent chance of La Nina conditions between December and February? La Niña expected to bring dry winter to Arizona (abc15.com)
A lack of snow in the Rocky Mountain watershed could push Arizona into a Tier 2 shortage on the Colorado River by 2023 according to the US Bureau of Reclamation’s (BOR) 24 month study. OPERATION PLAN FOR COLORADO RIVER RESERVOIRS (usbr.gov).
Central Arizona had already taken a voluntary cut of 192,000 acre feet a few years back to try keep the level of Lake Mead up in a futile attempt to stave off future cuts. As the two decade-old drought continued the BOR made a first-ever Tier 1 shortage declaration last August. This triggers an additional cut of 320,000 acre feet in Central Arizona’s water allocation. A full Tier 2 shortage would take another 128,000 acre feet. To put it in perspective these cuts which would total 640,000 acre-feet represent over half of the non-tribal water allocation from the Colorado River to Central Arizona cities and farms!
The Phoenix metro, looking ahead, had made preparations in previous years through conservation measures and banking water underground in times of surplus. Pinal County farmers, however, now bear the brunt of the current round of cuts. These farmers will have to return to groundwater pumping, fallowing up to half of their acreage, growing less water intensive crops (providing there is a market for them) and/or using new water saving technologies to survive.
If Lake Mead falls below 1025 feet this triggers a Tier 3 shortage which would require a cut of another 80,000 acre-feet from Central Arizona. Due to its conical shape, it takes less water to lower the lake’s elevation. Recently released modeling projections from BOR show a 66 percent chance of reaching Tier 3 by 2025. Arizona's water shortage: New projections for Colorado River | 12news.com
A Tier 3 cut would get the attention of average Arizonans since it would start to impact Phoenix area cities. While these cities have banked approximately 9 million-acre feet of water underground for just such emergencies, you can bet additional water conservation measures would be put in place for commercial and residential users. At that point, some people will finally begin to wonder what happened in this slow-motion crisis two decades in the making. Perhaps an upcoming La Nina will get their attention.