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In the dusty fields near the dry bed of the Gila River in Hyder, not far from the Agua Caliente ghost town, drilling rigs are boring deep into the ground. 

Companies have been buying land to lease to hay growers, and they re putting in new wells more than 1,500 feet deep, creating Arizona s next agricultural frontier for industrial farms. 

Mark Skousen runs a second-generation family farm near the abandoned hot spring in Hyder. When his father bought the land and drilled a well in 1957, the water gushed out of the ground. At that time, the Agua Caliente hot spring was still flowing.

In the early 1960s, when Skousen was a boy, another farmer drilled wells at a farm near the hot spring. When they started pumping, the water quit flowing out of the ground and the hot spring died.

The water tables s been dropping steady since then, Skousen said. 

Some of his wells no longer produce enough water and he has had to reduce the number of acres he farms. 

In the long term, the water losses may be irreversible in many rural communities. Much of the groundwater that s flowing to farmland accumulated underground thousands of years ago. As it s pumped out, the aquifers are suffering a hollowing-out that the rains won t replenish for centuries to come. 

In a few areas of the state, aquifers have been replenished by years of banking imported water from the Colorado River, and there, groundwater levels have risen.

But even in active management areas around Phoenix, Tucson and Pinal County, where aquifers have benefited from decades of regulation, there still have been significant declines in some areas. In more than half the subbasins in managed areas, average water levels have declined since the 1980s even with restrictions on groundwater pumping and additional CAP water.

Arizona faces its first-ever mandatory cuts in Colorado River water next year under an agreement that will shrink the amount of water that s available to replenish aquifers in urban areas. And in the long-term, with climate change projected to put growing strains on water supplies from rivers, Phoenix and other cities plan to potentially pump more groundwater. 

Groundwater also feeds desert streams and rivers, and decades of heavy pumping has left them with diminished flows. The future of remaining rivers, from the San Pedro to the Verde, hangs in the balance. 

Overpumping can also drive up costs.

At deeper levels, groundwater can contain higher levels of contaminants, which can require expensive treatment. And the deeper the water table falls, the more energy costs increase to pump the water out. 

If nothing changes, Ferris said, either the groundwater runs out, or it becomes too expensive to pump, or its quality is such that it s too expensive to treat to use.

Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.