2022. 9. 6. 13:28ㆍ■ 자연 환경/自然
Las Vegas isn't betting on Mother Nature to solve its water problems. Here's how it intends to win (msn.com)
Las Vegas isn't betting on Mother Nature to solve its water problems. Here's how it intends to win
Stephanie Elam - 17h ago
For a city in the desert, water conservation must be a way of life. But amid a prolonged megadrought that has depleted water resources across the Southwest, the need to save every drop has intensified in Southern Nevada.
Las Vegas knows the stakes are high, and it isn’t gambling on Mother Nature to solve its water problems.
Instead, the city is betting on extreme water-saving measures to keep the taps flowing. Here’s how it intends to win.
Bet 1: Banning mega-pools
Las Vegans are no longer allowed to build giant swimming pools or spas at single-family homes.
The Southern Nevada Water Authority says there’s been a proliferation of giant pools – some larger than 3,000 square feet – in recent years. The new building code limits new pools to no more than 600 square feet – a move the Las Vegas Valley Water District says will save more than 32 million gallons of water over the next decade. The average pool size in southern Nevada is 470 square feet.
The idea was to prevent people from building pools that were more like “water features” at some homes, rather than recreational swimming pools, said Bronson Mack, public outreach officer for the Water Authority, which manages water resources for 2.2 million people including Las Vegas.
“A lot of these more affluent homes, they’re not even occupied year-round,” Mack told CNN. “And yet they have all of this water in their backyard.”
Bet 2: Reclaiming all indoor water for reuse
Most of the Water Authority’s conservation efforts focus on outdoor water. But indoor water can be recycled.
“Water that we used indoors all gets reclaimed,” Mack said. “We treat that water to clean water standards, then return it to Lake Mead, our primary water source. Every gallon that we return to Lake Mead allows us to take another gallon out of the lake without counting against our limited water allocation.”
According to the Water Authority, only 10% of its water comes from local groundwater. The other 90% comes from the Colorado River’s Lake Mead, the largest man-made reservoir in the country, which continues to fall to record lows. In April, the Water Authority had to decommission one of the original intake valves in the lake because the water level had fallen so low.
And in August, the federal government enacted a Tier 2 shortage, which will limit the amount of water southern Nevada can pull from Lake Mead beginning in January by about 8.1 billion gallons a year.
Yet, on the Las Vegas Strip, glasses of water may still be served to restaurant customers since all that water will be recycled.
“Even if you don’t drink that glass of water … they’re going to dump that down the drain, and all of that water gets reclaimed,” Mack said, noting this practice began in the 1950s. “That dish is going to go through the dishwasher – all of the dishwasher water gets reclaimed and recycled back to Lake Mead.”
Bet 3: Keeping the Vegas Strip water-savvy
As for the Strip, the economic engine of southern Nevada, Mack said the region’s resort, casino and hotel sector is not as water-wasteful as it seems, despite its reputation for excess.
Mack said it only uses 5% of the community’s total water supply, while also making up its largest employment base, supporting some 40 million visitors a year.
There are also limitations on swimming pool size for the resorts based on the number of hotel rooms and guests they serve.
“We could turn on every shower and every sink in every hotel room on the Las Vegas Strip, and it wouldn’t increase the amount of water we deplete from the Colorado River because all of that gets cycled back through our wastewater system, gets treated and returned to Lake Mead,” Mack explained.
As for the Las Vegas strip’s iconic fountains? They lose a lot of water to evaporation. According to the Water Authority, the fountain at the Bellagio is fed from a privately owned groundwater well and doesn’t use water from the Colorado River. But it estimates those outdoor water features can lose 48 gallons of water per square foot a year to evaporation – in a place where every drop counts.
The canals in the Venetian Resort recirculate their water, which does come from Colorado River. However, since the water is used indoors it can be reclaimed, Mack said.
As the climate crisis intensifies and water resources decline, the Las Vegas Valley Water District is considering a ban on all new ornamental water features at resort hotels, unless the feature is completely indoors and supplied by a privately owned water source.
Bet 4: Tearing out ‘nonfunctional’ grass
Grass as been a major focus for conservation efforts in Las Vegas – especially grass that tends to be “nonfunctional,” or is merely ornamental, on medians, in front of commercial buildings and even in front yards.
Since April, the Las Vegas Valley Water District has banned grass and spray-irrigation systems at all new properties. Schools, parks and cemeteries are exempt. Single-family homes built after 2003 are prohibited from having grass in front yards and limited on how much they can have in side and back yards.
“We have removed more than 200 million square feet of grass from this valley, but there’s still about that much grass that remains,” Mack said.
While getting rid of grass has been more widely embraced by homeowners, businesses have been slower to adapt. However, in 2021 the Nevada legislature passed a law that bans irrigating nonfunctional grass with water from the Colorado River.
SNWA estimates the grass law will ultimately save 10% of its total water supply.
“That’s more water than is consumed by the entire Las Vegas Strip,” Mack said, explaining that it takes 73 gallons of water per square foot every year to keep grass alive in the Mojave Desert. But drip-irrigated and drought-tolerant landscaping only requires 18 gallons per square foot a year.
Watering grass “is the least efficient way” we can use water, Mack said.
Bet 5: Strict irrigation schedules year-round
The Water Authority also has a rotating watering schedule based on the time of the year.
As of September 1, outdoor watering is limited to three assigned days a week for the fall. On November 1, the winter schedule drops to one day a week before going back to three days for the spring, beginning March 1.
In the summer months, watering is permitted six days a week starting May 1, but never during the hottest time of day – between 11 a.m. and 7 p.m. – when the water is prone to evaporation in the desert heat.
Watering is always scheduled by neighborhood and is never permitted on Sunday.
Bet 6: Identifying water wasters
Since everyone in a community is on the same watering schedule, it makes it easy to identify the people and businesses flouting the rules.
The Water Authority has water waste investigators who will contact property owners, highlight the waste and give them a chance to fix the issue. If the problem isn’t addressed, the owners will be fined, starting at $80 and then doubling for every subsequent violation.
Mack said there’s still water waste happening daily, but the water authority has enforced these rules for about a decade.
“We had to be early adopters of that kind of activity,” Mack said.
Bet 7: Taking advantage of Mother Nature
When Mother Nature makes it rain, Las Vegas goes all in.
This summer, Las Vegas was hit with a couple of monsoonal rain storms that helped ease some of the region’s drought, but also left incredible damage in their wake. It only took a couple inches of rain for water to pour into casinos on the Strip.
Much of that storm water gets funneled into the Las Vegas Wash which flows out to Lake Mead. But even though it was a lot of water all at once, Lake Mead is huge, and it may only increase the lake level by fractions of an inch, Mack said.
What’s most important when it does rain in the Las Vegas Valley, Mack explained, is getting customers to shut their irrigation off.
During one week of extreme rain in August, the community turned off its irrigation systems and some of its air conditioning systems, which also use water.
“That collectively saved about 250 million gallons of water,” Mack said. “Saving water is desert living and we are in the middle of the Mojave Desert. Our community has been a city in the desert and now we are finally becoming a desert city.”
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