Disappearing groundwater is the out-of-sight, out-of-mind threat that can potentially change how and where we live and grow food, among other things. (Photo : Pixabay)

To counter the ongoing drought in the western United States, we are using aquifers to pump irreplaceable groundwater from the earth and into people's homes. But once this nonrenewable supply is tapped out, the real crisis begins.

Disappearing groundwater is the out-of-sight, out-of-mind threat that can potentially change how and where we live and grow food, among other things.

Groundwater comes from aquifers - sponge-like gravel and sand-filled underground reservoirs - that provide populations with freshwater to make up for surface water lost from drought-depleted lakes, rivers and reservoirs.

However, what we often don't realize is that as we continue to rely on this hidden resource, we are actually depleting a water supply that's used to meet half of our water needs, the US Geological Survey reports. The current drought shrinks surface water in lakes, rivers and reservoirs, and so we grow more dependent on groundwater from aquifers. Some shallow aquifers recharge from surface water, while others deep in the ground contain ancient, or "fossil," water locked in the earth - a supply that is not everlasting.

"These aquifers typically cannot recharge, and once this 'fossil' water is gone, it is gone forever," wrote National Geographic.

Deadly Droughts Leading to Water Scarcity

It's no secret that the western United States - as well as other parts of the world - is currently suffering from a three-year-long drought. The Colorado River Basin, for one, is drying up and losing water at dramatic rates. According to a NASA study published in the journal Geophysical Research Letters, the basin has lost nearly 53 million acre feet of freshwater since 2004, taking away far more water than the region can hope to refill - a real concern considering that it supplies water to 40 million people in seven states. Researchers also determined that more than 75 percent of this water loss is being replenished by underground resources.

"We don't know exactly how much groundwater we have left, so we don't know when we're going to run out," Stephanie Castle, a water resources specialist at the University of California, Irvine, explained in a NASA news release.

"We thought that the picture could be pretty bad, but this was shocking," she added.

Perhaps a more cited example, the ongoing California drought - now approaching four years long - has depleted snowpacks, rivers and lakes, and groundwater use has soared to make up the difference.

A new report from Stanford University says that nearly 60 percent of the state's water needs are now met by groundwater, up from 40 percent in years when rain and snow fall were normal.

California's Central Valley isn't the only place where water supplies are declining. Nature World News recently reported how water scarcity in Iran is becoming a national emergency. During the hot summer months, the nation has been fighting arid temperatures and notable water supply drops, with lower-than-average precipitation levels leaving the great majority of the region's dams and waterways under desired capacity.

While climate change is partly to blame for this water shortage, the people of Iran themselves are exacerbating the problem.

"Despite imminent shortages, water use in Iran remains inefficient, with domestic use 70 percent higher than the global average," the organization Future Directions International (FDI) reports.

An estimated 75 million people comprise the Iranian population, and the government continues to warn them that greater water conservation efforts are necessary.

However, this plan has backfired before.

"Several years ago there was water rationing. Each day, water would be cut for several hours in different parts of Tehran," environmental expert Esmail Karhom told local media, according to a report from the Orsam Water Bulletin. "Out of fear of running out of water, people would store so much water [before the scheduled cuts] that their consumption ended up being higher than usual."

Trying to Gain Ground

Relying on groundwater does make up for shrinking surface water supplies, but at a price. Well-drillers in California are working overtime to gain access to groundwater via aquifers, at a cost of more than $300,000 for a single well for all the farmers and homeowners waiting in line, according to National Geographic.

And given this increased drilling rate, aquifers aren't given enough time to recharge before they are pumped of water again. Worse still, as aquifers are depleted, the land also begins to subside, or sink.

Additionally, hydraulic fracturing - a water-intensive drilling process for oil and gas known as "fracking" - isn't helping. According to a February report from CERES, an organization that advocates sustainable business practices, more than one-third of these fracking wells are in regions already suffering groundwater depletion.

Now that we are aware of the problem, what are we doing to try to solve it? NASA's GRACE satellites, for one, have allowed us to more accurately understand groundwater supplies and depletion rates, National Geographic notes. GRACE has allowed us to identify which regions are particularly vulnerable to drought and shrinking water supplies - including northern India, the North China Plain and the Middle East.

China, also challenged by water scarcity, is planning a multi-billion dollar water transfer project to transfer water from the south to the north. However, researchers behind a study published in the journal Environmental Science & Technology claim that while international imports can lessen the water burden in strained regions, inter-province trade just makes things worse.

"Importing water-intensive goods from one water-scarce region to another doesn't solve the problem of water scarcity - it just shifts the pressure to other regions," study co-author Klaus Hubacek said in a statement.

As for the United States, there are currently no statewide regulations limiting groundwater use. State legislators are contemplating implementing such a policy, but even if it passes, compliance plans wouldn't be required until 2020, and full restrictions wouldn't kick in until 2040. Until then, California property owners can pump water to their heart's desire from under the ground they own.

"We're long overdue in California to treat groundwater as an integral part of our water supply system, and we need to not only address our use of groundwater with respect to quantity, but also quality," Assemblyman Roger Dickinson (D), author of the Assembly's version of the bill, told The Washington Post. "The old phrase 'never let a good crisis go to waste' applies."