HomeOur Water SupplyConsequencesLand Subsidence Threat
Print

Threat of Land Subsidence

Not Immediate But Long-Term Worry

When more groundwater is removed than is recharged, the water table declines. Pores in formerly saturated alluvium are no longer held open by water pressure, allowing the alluvium to compress, thus permanently lowering the land surface. This is land subsidence. The Arizona Geological Survey monitors known subsidence zones statewide using InSAR satellite technology.

In central and southern Arizona, beginning in the 1940s and continuing today, land subsidence in Arizona has already cost millions from damaged pipelines, collapsed wells, and cracked canals, roads, bridges, buildings, homes, and dams. Active subsidence regions include agricultural areas in the McMullen Valley, Scottsdale, Queen Creek, Luke AFB, Pinal County, and Willcox. A statewide risk assessment estimated potential damages at nearly $200 million.

An ADWR hydrologist (Frank Corkhill, private communication) stated, "At this time the amount of historic water level decline in the PrAMA would be considered generally too small to have caused any significant subsidence (compared to conditions in other areas of the state). However, that is more of a general observation than a hard and fast rule."  Satellite images obtained by CWAG from ADWR for the Little Chino Sub-basin show no detectable subsidence for the period 2005-2008.

Due to the potentially disruptive and expensive effects of subsidence, long-term subsidence monitoring is needed. If safe yield were to be achieved, groundwater levels would be stabilized and expensive, substantial damage to infrastructure and property could be avoided.

Updated June 12, 2023

DAILY DROPLET

  • "Ranchers need clean water for their stock, farmers need it for their crops, every employer needs it to stay in business, and every living thing needs it for life... The law needs to be clear to protect water quality and the rights of landowners."
    Mark Udall

  • "Water is the driver of Nature."
    Leonardo da Vinci

  • "When the well is dry, we know the worth of water."
    Benjamin Franklin, Poor Richard’s Almanac, 1746

  • "...and since flow of information is to spirit what water is to life, we'd best think about how to keep the pipes free and unclogged."
    Raphie Frank

  • "In an age when man has forgotten his origins and is blind even to his most essential needs for survival, water along with other resources has become the victim of his indifference."
    Rachel Carson

  • "We forget that the water cycle and the life cycle are one."
    Jacques Yves Cousteau

  • "Water is life's matter and matrix, mother and medium. There is no life without water."
    Albert Szent-Gyorgyi, 1937 Nobel Prize for Medicine

  • "Water is everywhere and in all living things; we cannot be separated from water. No water, no life. Period..."
    Robert Fulghum

  • "It's the water. Everything is driven by the water."
    Mike Thompson

  • "Whiskey is for drinking; water is for fighting over."
    Mark Twain