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Trickle-down drought: Arizona dodges connection between ground & surface water

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Killing the Colorado

Trickle-down drought: Arizona dodges connection between ground & surface water

  • If water levels drop enough at Lake Mead, the federal government will declare a shortage and Nevada and Arizona will face dramatic cuts in supply.
    Michael Friberg/ProPublicaIf water levels drop enough at Lake Mead, the federal government will declare a shortage and Nevada and Arizona will face dramatic cuts in supply.
  • East Park Reservoir, about 70 miles north of Sacramento.
    Sir EWD/FlickrEast Park Reservoir, about 70 miles north of Sacramento.
  • Lake Powell has recently fluctuated between 39 and 51 percent of capacity. If the drought ended tomorrow, it would take 10 years for it to fill back up.
    Michael Friberg/ProPublicaLake Powell has recently fluctuated between 39 and 51 percent of capacity. If the drought ended tomorrow, it would take 10 years for it to fill back up.

This story was originally published by ProPublica.

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Deep beneath the bleached-out, dusty surface of the drought-stricken West is a stash of water sequestered between layers of rock and sometimes built up over centuries.

Officials in the Colorado River basin states have long treated this liquid treasure as a type of environmental retirement account — an additional supply of water they can raid to get through the driest years and make up for the chronic overuse of the rivers themselves.

In recent years, the withdrawals have taken on even more importance: At least 60 percent of California’s water now comes from underground, some researchers say. Arizona, staring down imminent rationing of Colorado River water, pumps nearly half its supply from aquifers.

But in allowing their residents to tap underground resources this way, regulators and legislators in Southwestern states have ignored an inconvenient truth about how much water is actually available for people to use: In many places, groundwater and surface water are not independent supplies at all. Rather, they are interconnected parts of the same system.

The science has been clear for the better part of a century. Drawing groundwater from near a stream can suck that stream dry. In turn, using all the water in streams and rivers lessens their ability to replenish the aquifers beneath them. Farmers who drill new wells to supplement their supplies with groundwater are often stealing water from their neighbors who hold rights to the rivers above them. This understanding has been the foundation of the U.S. Department of the Interior’s water accounting for decades, and was used by the U.S. Supreme Court to decide one of the most significant water contests in history.

Yet California and Arizona — the two states water experts say are facing the most severe water crises — continue to count and regulate groundwater and surface water as if they were entirely separate.

“States have their own take on this. Or they choose to not address it at all,” said Stanley Leake, a hydrologist with the U.S. Geological Survey and a leading expert on properly accounting for the connection between ground and surface waters in the West. “In some cases they pretend that there is no connection.”

Leaders in California and Arizona acknowledge that their states have done this, at least in part to avoid the grim reckoning that emanates from doing the math accurately. There is even less water available than residents have been led to believe. If these states stopped effectively double-counting their resources, they would have to change laws, upend traditional water rights and likely force farmers and cities to accept even more dramatic cuts than they already face — a political third rail.

“The politics of water are more challenging than any other issue the state faces,” said Fran Pavley, a California state senator who helped draft a much-praised package of state laws passed last year regulating groundwater withdrawals for the first time.

Tucked into Pavley’s package was a little-noticed provision that explicitly prohibits California state regulators from addressing the interconnection between groundwater and surface water in local water plans until 2025, a compromise meant to give local water agencies a leisurely runway to adjust to a new way of counting. Pavley said the prospect of more immediately acknowledging the overlap between ground and surface waters threatened to derail the legislation entirely, triggering fierce opposition from the Agricultural Council of California, the California Chamber of Commerce and other industry groups.

“Those who have unlimited water supply don’t particularly like the idea of changing that,” she said. “You can’t manage what you don’t measure.”

Arizona law, too, treats groundwater and surface water as unconnected, as does Arizona’s state water plan, which purports to account for water resources and to estimate how many years of supply remain. Its authors know better, Arizona’s top water official acknowledged, but rewriting them to be more truthful would be politically impossible and economically damaging. “We know for a fact that pumping aquifers can dry up rivers,” said Thomas Buschatzke, the director of the Arizona Department of Water Resources, who says his policy is bound by the Legislature and court rulings. “But it is the law … it would be a huge upset to the economy to do away with that.”

The costs of refusing to acknowledge or adapt to the reality that two seemingly separate sources of water are actually often one are hard to measure but may turn out to be profound, leading hydrologists say.

In a series of articles, ProPublica has been examining the ways in which man’s mistakes in managing water in the West have exacerbated the severity of the drought and have left Colorado River basin states less able to adapt to a changing climate. There are lots of culprits: farming subsidies for water-intensive crops, arcane laws encouraging waste, leaky infrastructure and more.

But none may be more significant than allowing a miscounting of how much water exists in the first place. Willingly overlooking the science amounts to a fundamental failure of water management, leading water experts say, one that is leading to decisions about how to use it that will deepen and prolong the drought’s painful effects. In the end, said Rich Juricich, an engineer with the California Department of Water Resources, it may mean that some places run short of the water they need.

Already, damage from the West’s increasing reliance on underground water supplies is proliferating. In parts of California and Arizona, groundwater levels are being drawn down so quickly that the earth above them is collapsing. Bridges and canals are buckling.

The more water is extracted from underground, the harder it becomes to restore the region’s rivers and reservoirs — some of which no longer flow through the summer — simultaneously sucking them dry from above and below.

“If you don’t connect the two, then you don’t understand the system,” said John Bredehoeft, a leading hydrogeologist who for many years managed the U.S. government’s western states water program for the U.S. Geological Survey. “And if you don’t understand the system, I don’t know how in the hell you’re going to make any kind of judgment about how much water you’ve got to work with.”

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