Heavy monsoon rains have helped to relieve the Southwest’s historic drought, but water officials say the deluge isn’t enough to reverse a drying trend that has depleted the region’s primary water sources.
Much of the West remains entrenched in a 23-year “historically unprecedented” drought driven by climate change, said Jonathan Deason, an environmental engineering professor at George Washington University.
“It’s going to take about three years of above-average rainfall to have substantial recovery,” he said.
Most of the Southwest has received more than double its normal amount of rain since June, according to the latest US Drought Monitor. Some areas, especially in New Mexico, have seen drought conditions improve over the summer from exceptionally extreme to just severe or abnormally dry.
“In the short term, there has been great relief, and we expect that to continue well into the fall,” Mike Hamman, New Mexico’s state water engineer, told Bloomberg Law.
The monsoons aren’t enough to combat the long-term trend toward hotter, drier weather in the West, said Ben Frech, spokesman for the National Groundwater Association.
“You’re not going to monsoon your way out of a historically long and severe drought,” Frech said.
Colorado River Shortage
Extreme drought conditions led the Bureau of Reclamation to declare a first-ever shortage on the Colorado River, which provides water for 40 million people from Denver to Los Angeles.
The bureau in May said it will withhold 480,000 acre-feet of water from Lake Powell in 2022 to prevent the reservoir from dropping so low it can no longer generate electricity,.
The agency in June asked the seven Colorado River Basin states to create a plan by this month to drastically cut the water they use from the river in 2023 to alleviate the shortage. The Upper Colorado River Basin states of Utah, New Mexico, Colorado and Wyoming responded in July with a five-point water conservation plan.
The Bureau of Reclamation declined to immediately respond to questions about the Colorado River Basin shortage.
Mead Decline Halted
The monsoon rains have for now halted the decline of lakes Powell and Mead, the largest reservoirs on the Colorado River.
Lake Mead, where drought conditions are most acute, has risen about 1% due to rainfall since it hit its record low level on July 28, said Richard Tinker, author of the US Drought Monitor at the US Climate Prediction Center in Maryland. The lake has receded so much that authorities have discovered several sets of human remains that may have been dumped there.
“Rainfall from recent monsoons alone isn’t enough to offset the decades-long reservoir declines,” a Bureau of Reclamation spokesperson said via email.
Melting snow is still the main water source for Lake Mead, and though the monsoons help, they’ve only contributed to a few inches of re-fill in the lake, she said.
There is a long-term downward trend in the lake level that isn’t sustainable long term, Tinker said. New reservoirs and desalination plants will be needed to shore up the region’s water supplies, he said.
New Mexico is preparing for the drying trend to continue so it can ensure enough water is in the Colorado and Rio Grande rivers to meet the state’s legal obligations to deliver sufficient water to downstream water users, Hamman said.
In California, Gov. Gavin Newsom (D) last week released a new plan designed to boost water supplies in the face of worsening droughts. But Newsom stopped short of calling for mandatory statewide home water-use restrictions.