New homes that depend on dwindling groundwater supplies around one of the largest US cities will be banned Thursday, officials said, in a sign of pressures caused by drought and climate change across the western US.
Arizona water managers say there is a major shortage in the Phoenix area, and that any further development in the fast-growing city would have to rely on other sources of water — like rivers under pressure.
“Over 100 years, the Phoenix area will see 4.86 million acres of unmet demand for groundwater supplies,” said the Arizona Department of Water Resources.
An acre foot is the amount of water needed to cover an acre by foot of water—about 326,000 gallons (1.23 million liters)—which is about half an Olympic-sized swimming pool.
“The term ‘unmet demand’ refers to the amount of groundwater use that is simulated to remain unmet as a result of wells drying up.”
The western United States is in the grip of more than two decades of drought and a prolonged drought, which scientists say is being exacerbated by human-caused climate change.
The major rivers that traverse the area, the Colorado River among them, have long been overexploited, with far more water being removed each year than falls as rain or snow.
This has led to shrinking reservoirs, including mighty Lake Mead, which last year fell to only a quarter of its capacity, threatening a “dead pool” — the point at which a river dries up downstream and hydroelectric production ceases.
With rivers under pressure, rapidly growing population centers have long had groundwater to provide water for homes and agriculture, in the form of wells.
But this resource is easily overexploited and can in some cases take thousands of years to be replenished.
State officials said permits already issued for developments in Maricopa County, where Phoenix is located, will not be revoked, but developers will have to prove that any new applications have a sustainable water source other than groundwater.
The Arizona Department of Water Resources said, “Limitations in the physical availability of groundwater are the cumulative results of decades of over-abundance of groundwater and continued reliance on groundwater resources.”
Phoenix, the fifth largest city in the country, is home to about five million people and is one of the fastest growing metropolitan areas in the United States.
Thursday’s announcement is the latest move in a long battle over the waters in the western United States.
Last month, states that depend on the Colorado River reached an agreement on reducing the amount of water they take from the region’s lifeline.
About 40 million people including Los Angeles, Las Vegas and Phoenix depend on the river.
But what was once one of the world’s largest rivers has now shrunk.
Human-caused climate change means that the once abundant snowpack feeding the river has diminished.
The snow there is melting more quickly due to higher temperatures, and more is being lost to evaporation.
Wet winters in the western United States have relieved some stress on the system, scientists say, but this is only a temporary reprieve because human-caused climate change continues to exacerbate the long-term drying trend.
© 2023 AFP
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