#megadrought

Pictured: Visitors, shown as black silhouettes, take in the free water show at the Bellagio resort on the Las Vegas Strip.

Fountains still shimmer opulently at casinos on the Las Vegas Strip, but lush carpets of grass are gradually disappearing along the streets of Sin City.

Despite its reputation for excess, the Mojave Desert metropolis has been factoring climate change into its water plans for years, declaring war on thirsty lawns, patrolling the streets for water wasters and preparing for worst-case scenarios on the Colorado River, which supplies 90% of the area’s water.

Las Vegas has emerged as a leader in water conservation, and some of its initiatives have spread to other cities and states that rely on the shrinking river. Its drive to get rid of grass in particular could reshape the look of landscapes in public and private spaces throughout the Southwest.

So how did Las Vegas become a water-saving model to emulate? It began with an initial phase of the Colorado River crisis two decades ago.

Lake Mead had been nearly full and lapping at the spillway gates of Hoover Dam in early 2000. Then extreme drought and heavy water use sent the reservoir into a rapid decline.

In 2002, as the reservoir level dropped, the Southern Nevada Water Authority used more than its allocation of Colorado River water. At that point, the agency’s leaders decided to pivot quickly toward conservation.

They focused on promoting cash rebates to help customers rip out lawns and put in landscaping with desert plants.

In 2003, the Las Vegas area’s consumption of Colorado River water shrank more than 16%. Those conservation gains continued as the area’s water suppliers strengthened their rules, targeting grass.

In 2004, frontyard lawns were prohibited for new subdivisions. Golf courses were given water budgets. The water authority adopted seasonal watering restrictions.

Pictured: The suburban community of Mountain’s Edge, which has rock- and shrub-based yards instead of lawns, cuts a square through the barren-looking desert. In 2004, frontyard lawns were prohibited for new subdivisions in the Las Vegas area.

Since 2002, southern Nevada’s use of Colorado River water has decreased about 26%, even as the area’s population has rapidly grown. Per capita water use has dropped 48%.

And Las Vegas is continuing to tighten its restrictions on grass.

The state Legislature in 2021 passed a law that bans watering all decorative “nonfunctional” grass along streets, on medians, at homeowners associations, apartment complexes, businesses and other properties starting in 2027.

“For Las Vegas to be sustainable, it’s imperative,” said Colby Pellegrino, the water authority’s deputy general manager of resources. “That’s the first time we’ve actually said existing turf should no longer be watered.”

Since 2002, homeowners and others in the Las Vegas area have already removed about 205 million square feet of lawn, or more than 4,700 acres. The drip-irrigated plants and trees that replaced the grass require less than one-fourth the amount of water, saving an estimated 11.4 billion gallons per year.

In the next four years, much more grass is about to be ripped out. And newly built homes can no longer have any lawns at all, including in the backyard.

Grass will still be permitted for new parks, schools and cemeteries.

Las Vegas’ eradication of grass offers a view of the sorts of changes that other cities have been starting to adopt and may soon be forced to pursue on a larger scale as the river continues to decline...

Las Vegas is one of many cities along the Colorado River that have made major progress in reducing water use over the last two decades. In a recent study, researcher Brian Richter surveyed 28 urban water utilities and found that total water use in the cities dropped by 18% between 2000 and 2020, even as their combined population grew by 24%...

“Las Vegas has become a water conservation rock star in recent decades,” Richter said. “Their leadership in reducing outdoor water use is of particular importance.”

He said the area’s “cash for grass” program has become a model for cities across the West.

“The fact that they’ve now adopted a goal of further reducing their water use by another 23% by 2035 is truly admirable,” Richter said.”

The megadrought that has parched the southwestern United States and parts of Mexico over the last two decades is the worst to hit the region in at least 1,200 years, researchers said Monday.

Human-caused global heating accounts for more than 40 percent of the dry spell's intensity, they reported in the journal Nature Climate Change.

"The turn-of-the-21st-century drought would not be on a megadrought trajectory without anthropogenic climate change," lead author Park Williams, an associate professor at the University of California in Los Angeles, and colleagues wrote.

Excerpt from this story from National Geographic:

Water levels usually peak in May at Folsom Lake in California, rising as Sierra Nevada snowpack melts away and courses down to the reservoir, near Sacramento.

But this year, the drought that has gripped much of the U.S. West is already so strong that the lake is only half as full as normal. Instead of water, fields of purple lupines line vast swaths of dry lakebed.

Folsom Lake’s situation is emblematic of the deepening drought across the western United States. As of May 6, 67 percent of the region was in a state of “severe” drought or worse; a stunning 21 percent is already in “exceptional” drought, the worst category in the U.S. Drought Monitor’s framework. At Lake Mead, one of the two major reservoirs of the Colorado River, which some 40 million Americans depend on, water levels are creeping toward a threshold that would trigger the first official shortage declaration for the basin.

The situation is unlikely to improve in the near future, scientists say, as 2021 shapes up to extend the “megadrought” that researchers have found to be gripping the region mostly unabated since 2000.

The region would have been in a state of drought regardless, “but it’s really climate change that pushed this event to be one of the worst in 500 years,” says Ben Cook, a climate scientist at Columbia’s Lamont Doherty Earth Observatory.

Drought can take many forms. There’s “meteorological drought,” which compares how much rain or snow has fallen compared to a long-term average. There’s “hydrological drought,” which considers how much water flows through streams and rivers and is stored in mountain snowpack and underground aquifers. There’s the drought the soil, plants, and animals feel, called agricultural or ecological drought.

This year, by just about every measure, the West is extremely low on water. Most of California and the Four Corners states are somewhere between 25 and 50 percent of their long-term averages on most of the drought indicators. Snowpack in California on April 1, its usual peak time, hit only 59 percent of its long-term average and has already largely melted away, leaving it at a paltry 15 percent of its average at this date. Soils are parched. The Colorado and Rio Grande rivers are trickling compared to their long-term histories.