The Las Vegas strip endures more flooding in monsoonal downpours but the drought relief those rains offer is limited.

Lake Mead, the water source for Las Vegas, Phoenix, San Diego and southern California agriculture, home to 1/3 of the country’s fresh vegetables, is up 14″ but down 179 ft. since 2000 to a record low. Rains won’t break the current drought because any relief is limited and temporary.

Drenching monsoonal rains have hit the drought ravaged West, flooding the Las Vegas strip at times in recent weeks. But what impact have the downpours had on the concerning record low reservoir levels there?

Monsoonal downpours have flooded the Las Vegas Strip in recent days, and Las Vegas isn’t alone in racking up big rain numbers with the current monsoon. Sections of Arizona have seen more than 400% of their precip to date.

The Southwest monsoon season was redefined in 2008 as running from Jun. 15 through Sept. 30. Prior to 2008, the onset of a particular monsoon season was defined by the achievement of an elevated dew point. The Jun. 15-Sept. 30 designation standardizes the period viewed as the monsoon season.

Of the Southwest monsoon, the Univ of Arizona’s Climate Assessment group says, “Arizona and New Mexico receive up to half of their annual rainfall during the summer monsoon. The monsoon season suppresses much of the hot summer temperatures, replenishes water resources, and nourishes the vegetation.

The monsoon arrives with much flash and fanfare, with its trademark thunderstorms and flooded streets in southwestern cities. Monsoon rainfall events tend to be short and spotty, with intense, local storms drenching some neighborhoods but not others. The water the storms bring quickly flows off the landscape into streets and rivers, with much of the remnant moisture evaporating in the summer sun.

The monsoon’s driving rains are most dramatic in southeast Arizona and in western New Mexico, tapering off in Phoenix and Yuma, AZ. In addition to being variable in space, some years produce weak monsoons, while others provide ample rain. There are no evident trends in annual monsoon strength, making it difficult to predict. This variable tendency has been consistent over the past 100 years when record keeping generally began.”

(READ THE FULL ASSESSMENT HERE: The forecast going into the 2022 Southwest monsoon season was for one likely to produce ABOVE NORMAL precip. It’s lived up to that billing as we move past the halfway mark of the season. The monsoon takes on special significance in the midst of a drought in the Southwest widely recognized as one of the–if not THE— worst in the region of the past 1,200 years.

NOW THE BIG QUESTION: How has this impacted drought in the area? Much attention has been paid to the record low lake levels in Lakes Mead and Powell, critical sources of water for 40 million across seven western states including southern California to Nevada, Arizona, Utah and New Mexico. They’re also the primary sources of water for Las Vegas, Phoenix and San Diego among other regions.

Going into the current 2022 monsoon season, Lake Mead outside Las Vegas–the nation’s largest reservoir—dropped to 27% of capacity–its lowest level since the Hoover Dam was built across the Colorado River from 1931-1936.

The Las Vegas Review Journal reports “Lake Mead’s unusual summer rise likely aided by monsoon season. Several factors influence its level, but recent rain has helped Lake Mead rise 15 inches in the past two weeks.” But the region is far from out of the woods with the recent rains. Lake Mead has dropped 179 ft. since 2000–so while the 15″ rise is beneficial, Bloomberg quotes officials in the area with humbling assessments of the water situation there:

“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.
Here’s a Newsweek Magazine report on the Las Vegas Strip.