Climate Change Caused Droughts in the West—Now Water Supply Is At Risk

Dwindling water supplies and below-average rainfall have consequences for those living in the West.

Little Washoe Lake on July 15, 2021 in Washoe City, Nevada. According to the Nevada Department of Wildlife, the lake dried up because of prolonged drought.
Little Washoe Lake on July 15, 2021 in Washoe City, Nevada. According to the Nevada Department of Wildlife, the lake dried up because of prolonged drought.

David Calvert/Getty Images

Across the western U.S., reservoirs are shrinking. The lack of rain and below-average snowfall in the Colorado River Basin combined with record-shattering temperatures have worsened an already alarming situation. Drying up under the baking heat, many of these reservoirs—victims of climate change and a severe, multi-year drought—have dropped to historically low levels. 

The nation's largest reservoir, Nevada’s Lake Mead, is only at 36% capacity falling to its lowest level since being filled in the 1930s following the completion of the Hoover Dam. Upstream in Utah, Lake Powell, at just 34% full, could reach its own record-low watermark by next spring if water levels continue to decline as predicted. 

But one of the most drastic drops, as witnessed in dramatic aerial photographs, is Lake Shasta in California. In July 2019, the Shasta reservoir stood at a robust 94% capacity but in a period of only two years, it has shriveled to its current level of 37%. Other California reservoirs are seeing a similar decline. Lake Oroville and the San Luis Reservoir are both 31% full, while Lake Isabella is at 13% capacity. 

It’s a case of a population using more water than storms replenish. Dwindling water supplies in reservoirs and below-average rainfall have already had a multitude of consequences for those living in the West. Water conservation efforts are being ramped up. Farmers and ranchers are struggling to grow crops and feed livestock. Wildlife is being forced to search for water in a parched landscape and hydropower plants are putting out less energy as reservoirs retreat. 

And the problem isn’t limited to the Colorado River, Lake Mead and Lake Powell as shrinking lakes and rivers is a worldwide problem

Rising temperatures and climate change is being blamed for what scientists have begun to call a “megadrought.” As of July 13, 89% of the western U.S. was considered to be under drought conditions, according to the National Integrated Drought Information System, a climate monitoring organization. 

What NIDIS found is that 76.7 million Americans are living in drought conditions, 46% of the lower 48 states are experiencing drought and 185 million acres of farmland are affected by it. 

Breaking it down by region the numbers show how extreme the western dry-out is. It labels the entire states of California and Nevada and 86% of the Pacific Northwest as being in drought, with Idaho, Oregon, and Washington experiencing the second driest spring on record since 1895. 

With 52% of California in extreme drought and a third of the state declared to be in exceptional drought, Gov. Gavin Newsom (D) announced last week that he was expanded drought emergency status to 50 of California’s 58 counties covering about 42% of the state’s population. He also asked Californians to voluntarily attempt to cut their own water use to avoid mandatory restrictions.

“We’re hopeful that people will take that mindset they brought into the last [2012-2016] drought and extend that forward with a 15% voluntary reduction, not only on residences but industrial commercial operations and agricultural operations,” Newsom said at a press conference in San Luis Obispo County telling reporters it’s caused by climate change. “It’s here, and it’s human-induced. I think in the state of California we’ve moved beyond the debate and are moving toward finding a solution.”

The excessive, mostly triple-digit heat that has engulfed the region in recent weeks is only adding to concerns with warmer temperatures evaporating water more quickly and drying out plants and soil to a point where wildfires burn hotter and faster impacting wildlife habitats. 

A recent climate change study by researchers at the University of Arizona analyzing daily meteorological data from 1976 to 2019 at 337 long-term weather stations across the western U.S., found that as average temperatures have increased and annual rainfall has decreased, that periods of drought have become longer and more intense, especially in the desert Southwest. 

Across the West, total annual rainfall has decreased by about 0.4 inches since the 1970s, according to the report, and the average dry period between significant rain events has increased from 20 to 32 days. 

View Article Sources
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  2. "National Current Conditions." National Integrated Drought Information System.

  3. Hartman, Adam, and Curtis Riganti. "West." U.S. Drought Monitor, 2021.

  4. Zhang, Fangyue, et al. "Five Decades of Observed Daily Precipitation Reveal Longer and More Variable Drought Events Across Much of the Western United States." Geophysical Research Letters, vol 48, no. 7, 2021, doi:10.1029/2020gl092293.