The California Central Valley has major problems from subsidence, which is collapsing ground caused by pumping too much water out. Arizona has the same problems too, however stricter rules regulating groundwater pumping in some areas there have slowed subsidence substantially. If there are no regulations, subsidence gets worse.
This is not a trivial issue. Subsidence damages pipelines, roads, canals, bridges, and more.
Subsidence has been a problem in Arizona for decades. It’s the collapsing of the soil due to chronic pumping that exceeds the rate the aquifer is replenished by rainfall and other sources.
But today, where state regulations on pumping are stricter and renewable supplies are available — like Tucson — it’s getting better. In places like Willcox in Southeast Arizona’s Cochise County, and in parts of La Paz County in Western Arizona, where such regulations and renewable waters are non-existent, it’s getting worse.