9 Facts About California’s Groundwater

With an alarmingly dry winter and California reservoirs dropping fast, groundwater increasingly is keeping the state hydrated. It now accounts for about 60 percent of California’s water supply. But unlike its rivers, lakes and reservoirs, the state does not consider groundwater part of the public good. It does not regulate groundwater like it does surface water. Landowners can pump as much water as they want.

So for nearly a century, Californians have drained an incredible amount of water from the ground to grow crops and water landscaping. It is not sustainable. The water has not returned. The result is a sinking state. Here are some startling facts about California’s groundwater depletion:

  1. Californians drained about 125 million acre-feet of groundwater (about 41 trillion gallons) from the Central Valley between 1920 and 2013, according to the U.S. Geological Survey.That’s the equivalent of draining about a third of Lake Erie or, put another way, enough fresh water to provide every person on Earth with a 30-year supply of drinking water. Unfortunately, this reliance on groundwater seems to be worsening. The rate of aquifer depletion experienced during the past decade is more than double the historic average
  2. California is sinking at a record pace –one farmer in the Central Valley reported his land sank more than 18 inches last year.As the below-ground aquifers are drained, the land sinks to partially fill the space left by the removed water. Scientists call this subsidence. Most people call it scary. It first was documented in California in the 1930s. It primarily affects farmland since farmers use about 80 percent of the state’s water although, historically, cities such as San Jose and San Luis Obispo have experienced costly subsidence, too. Back in the 1960s, California farmland in the Central Valley was sinking at a record pace. By the late 1970s, some areas had sunk about 30 feet. It cost the state more than $1 billion to fix just some of the damage, which included sinking bridges, cracking canals and buckling highways, according to one estimate. The sinking took off again in 2008, and farmland now is dropping at a record pace. At least one agricultural area in the Central Valley is on pace to sink 30 feet – the equivalent of a three-story building – by 2030.
  3. It will take at least 50 years for the Central Valley’s aquifers to naturally refill, according to the U.S. Geological Survey.But that’s only if everyone stopped pumping groundwater immediately. That’s because the aquifers naturally refill at a rate of about 2 million acre-feet a year (650 billion gallons) as rain and snowmelt from the mountains seep underground, according to Claudia Faunt, a government hydrologist. But she stressed that this was only an estimate. Since California doesn’t consider groundwater a public good, no government agency is closely monitoring it, including exactly how many years it will take to replace all that drained water, she said. Even so, no one believes it’s economically prudent or humanely advisable to immediately stop pumping groundwater so the aquifers can refill. That’s because researchers studying the drought at the University of California, Davis determined this year’s water shortage, which equates to a 2.5 million acre-feet shortfall,will cost the state $2.7 billion. If California farmers, who produce almost half of all the fruits, nuts and vegetables grown in the United States, stopped pumping groundwater, it almost certainly would send food prices soaring. And what happens when food prices go up? People around the world starve.
  4. California has permanently lost about 18 million acre-feet (6 trillion gallons) of water during the past century, according to the U.S. Geological Survey.Aquifers partially collapsed as they were drained and forever reduced the state’s capacity to store water underground. So even if the state’s aquifers are miraculously refilled, it will be with 6 trillion gallons less, which is enough water to give every humanwho has ever lived since the beginning of time a 55-gallon oil drum full of water.
  5. California now is pumping water that is20,000 years old.Groundwater levels have been at historic lows in most of the state since 2008, according to the California Department of Water Resources. People are drilling so deep to find water – sometimes thousands of feet – that the water being pumped to the surface seeped underground when California still was home tomastodons, an ancient creature that resembles modern elephants.
  6. A great swath of the Central Valley is desert.Some of the bright-green farmland in the San Joaquin Valley gets only about 5 inches of rain a year – that’s just an inch more than Riyadh, the capital of Saudi Arabia. Before irrigation, much of the Central Valley was parched ground, cactuses and slow-growing shrubs. Now it’s increasingly covered in nut trees like pistachios and almonds, or thirsty grapevines, which are water-intensive crops and incapable of being fallowed during drought years. Overall, the Central Valley doesn’t get much rain. So as these water-intensive crops have been planted during the past decade, demands on water have surpassed the capacity of the massive irrigation canals built more than 50 years ago. The result? See No. 1 and No. 2 above.

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