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Arizona limits building as groundwater dries up

Published : 03 Jun 2023 01:04 AM

New houses that rely on dwindling groundwater supplies around one of the United States' biggest cities are to be banned, officials said Thursday, in a sign of the strains that drought and climate change are causing across the US west.

Water managers in Arizona say there is a significant shortfall in the Phoenix area, and that any more development in the fast-growing city must rely on other sources of water -- such as under-strain rivers.

"Over a period of 100 years, the Phoenix (area) will experience 4.86 million acre-feet of unmet demand for groundwater supplies," the Arizona Department of Water Resources said.

An acre-foot is the amount of water it takes to cover an acre with a foot of water -- around 326,000 gallons (1.23 million liters) -- and is equivalent to around half an Olympic-size swimming pool.

"The term 'unmet demand' refers to the amount of groundwater usage that is

simulated to remain unfulfilled as a result of wells running dry."

The western United States is in the grip of a more-than two- decade drought

and a long-term aridification, which scientists say is being exacerbated by

human-caused climate change.

Major rivers that cross the region, among them the Colorado River, have long

been over-exploited, with far more water removed every year than falls as

rain or snow.

This has led to shrinking reservoirs, including the enormous Lake Mead, which

last year dropped to just a quarter of its capacity, threatening "deadpool" -

- the point where the river downstream dries up and hydroelectric power

production ceases.

With rivers under pressure, fast-growing population centers have long tapped

groundwater to provide water for homes and agriculture, in the form of wells.

But this source is easily over-exploited and can in some cases take thousands

of years to be replenished.

State officials said permits already issued for developments in Maricopa

County, in which Phoenix sits, will not be rescinded, but developers will

have to prove any new applications have a sustainable water source other than


"The constraints regarding the physical availability of groundwater are

attributable to the cumulative results of decades of groundwater overdraft

and the continued reliance on groundwater resources," the Arizona Department

of Water Resources said.

Phoenix, the country's fifth largest city, is home to around five million

people and is one of the fastest growing metropolitan areas in the United


The announcement Thursday is the latest move in a long battle over water in

the US West.

Last month states that rely on the Colorado River reached an agreement on

cutting the amount of water they take from the lifeblood of the region.

Around 40 million people including in Los Angeles, Las Vegas and Phoenix

depend on the river.

But what was one of the world's great rivers has now shrunk.

Human-caused climate change means the once-bountiful snowpack that feeds the

river has dwindled.

What snow there is melts more quickly because of higher temperatures, and

more is lost to evaporation.

Scientists say a wet winter in the US West has alleviated some pressure on

the system, but this is only a temporary reprieve as human-caused climate

change continues to exacerbate a long-term drying trend.