Wells that people drill to access groundwater supply nearly half the water used for irrigated agriculture in the U.S. and provide over 100 million Americans with drinking water. Unfortunately, pervasive pumping is causing groundwater levels to decline in some areas, including much of California's San Joaquin Valley and Kansas' High Plains.
We are a water resources engineer with training in water law and a water scientist and large-data analyst. In a recent study, we mapped the locations and depths of wells in 40 countries around the world and found that millions of wells could run dry if groundwater levels decline by only a few meters. While solutions vary from place to place, we believe that what's most important for protecting wells from running dry is managing groundwater sustainably – especially in nations like the U.S. that use a lot of it.
The U.S. has one of the highest national groundwater use rates in the world. Jasechko and Perrone, 2021,
Groundwater Use Today
Humans have been digging wells for water for thousands of years. Examples include 7,400-year-old wells in the Czech Republic and Germany, 8,000-year-old wells in the eastern Mediterranean, and 10,000-year-old wells in Cyprus. Today wells supply 40% of water used for irrigation worldwide and provide billions of people with drinking water.
Groundwater flows through tiny spaces within sediments and their underlying bedrock. At some points, called discharge areas, groundwater rises to the surface, moving into lakes, rivers and streams. At other points, known as recharge areas, water percolates deep into the ground, either through precipitation or leakage from rivers, lakes and streams.
Groundwater can remain underground for days to millennia, depending on how deep it sinks, how readily it moves through rock around it and how fast humans pump it to the surface.
Groundwater declines can have many undesirable consequences. Land surfaces sink as underground clay layers are compacted. Seawater intrusion can contaminate groundwater reserves and make them too salty to use without energy-intensive treatment. River water can leak down to underground aquifers, leaving less water available at the surface.
Groundwater depletion can also cause wells to run dry when the top surface of the groundwater – known as the water table – drops so far that the well isn't deep enough to reach it, leaving the well literally high and dry. Yet until recently, little was known about how vulnerable global wells are to running dry because of declining groundwater levels.
There is no global database of wells, so over six years we compiled 134 unique well construction databases spanning 40 different countries. In total, we analyzed nearly 39 million well construction records, including each well's location, the reason it was constructed and its depth.
Our results show that wells are vital to human livelihoods – and recording well depths helped us see how vulnerable wells are to running dry.
Millions of Wells at Risk
Our analysis led to two main findings. First, up to 20% of wells around the world extend no more than 16 feet (5 meters) below the water table. That means these wells will run dry if groundwater levels decline by just a few feet.
Second, we found that newer wells are not being dug significantly deeper than older wells in some places where groundwater levels are declining. In some areas, such as eastern New Mexico, newer wells are not drilled deeper than older wells because the deeper rock layers are impermeable and contain saline water. New wells are at least as likely to run dry as older wells in these areas.
Wells are already going dry in some locations, including parts of the U.S. West. In previous studies we estimated that as many as 1 in 30 wells were running dry in the western U.S., and as many as 1 in 5 in some areas in the southern portion of California's Central Valley.
Households already are running out of well water in the Central Valley and southeastern Arizona. Beyond the Southwest, wells have been running dry in states as diverse as Maine, Illinois and Oregon.
What to Do When the Well Gives Out
How can households adapt when their well runs dry? Here are five strategies, all of which have drawbacks.
– Dig a new, deeper well. This is an option only if fresh groundwater exists at deeper depths. In many aquifers deeper groundwater tends to be more saline than shallower groundwater, so deeper drilling is no more than a stopgap solution. And since new wells are expensive, this approach favors wealthier groundwater users and raises equity concerns.
– Sell the property. This is often considered if constructing a new well is unaffordable. Drilling a new household well in the U.S. Southwest can cost tens of thousands of dollars. But selling a property that lacks access to a reliable and convenient water supply can be challenging.
Chart: The Conversation, CC BY-ND. Source: Jasechko and Perrone 2020
– Divert or haul water from alternative sources, such as nearby rivers or lakes. This approach is feasible only if surface water resources are not already reserved for other users or too far away. Even if nearby surface waters are available, treating their quality to make them safe to drink can be harder than treating well water.
– Reduce water use to slow or stop groundwater level declines. This could mean switching to crops that are less water-intensive, or adopting irrigation systems that reduce water losses. Such approaches may reduce farmers' profits or require upfront investments in new technologies.
– Limit or abandon activities that require lots of water, such as irrigation. This strategy can be challenging if irrigated land provides higher crop yields than unirrigated land. Recent research suggests that some land in the central U.S. is not suitable for unirrigated "dryland" farming.
Households and communities can take proactive steps to protect wells from running dry. For example, one of us is working closely with Rebecca Nelson of Melbourne Law School in Australia to map groundwater withdrawal permitting – the process of seeking permission to withdraw groundwater – across the U.S. West.
State and local agencies can distribute groundwater permits in ways that help stabilize falling groundwater levels over the long run, or in ways that prioritize certain water users. Enacting and enforcing policies designed to limit groundwater depletion can help protect wells from running dry. While it can be difficult to limit use of a resource as essential as water, we believe that in most cases, simply drilling deeper is not a sustainable path forward.
Debra Perrone is an assistant professor of environmental studies at the University of California Santa Barbara.
Scott Jasechko is an assistant Professor of water resources at the University of California Santa Barbara.
Disclosure statement: The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
Reposted with permission from The Conversation.
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Funded by the California legislature in 2018, the new report involved a literature review, scientific symposium for experts, peer review process, and public comment period. Its conclusions about the behavioral effects of food dyes are grounded in the results of 27 clinical trials in children performed on four continents over the last 45 years, as well as animal studies and research into the mechanisms through which dyes exert their behavioral effects.
Food dyes in products such as breakfast cereals, juice and soft drinks, frozen dairy desserts, candies, and icings were linked to adverse neurobehavioral outcomes in children including inattentiveness, hyperactivity, and restlessness. Animal studies also revealed effects on activity, memory, and learning.
The report is the most rigorous assessment of the behavioral effects of food dyes ever conducted, said Lisa Lefferts, a senior scientist with the Washington, D.C.-based nonprofit Center for Science in the Public Interest. (Editor's note: Lefferts previously worked as an editor at EHN).
Lefferts has been tracking the issue for years and through the Center published her own report on the link between synthetic food dyes and behavioral problems in children in 2016. In it she called for the U.S. Food and Drug Administration (FDA) to either revoke approvals for all food dyes or institute a federal labeling rule.
The European Union enacted such a law in 2010 that requires most dyed foods to bear a label warning consumers that food colorings "may have an adverse effect on activity and attention in children." In response, many food manufacturers reformulated their products for the European market to avoid the dyes, and thus the label.
But many left the dyes in their products for the U.S. market, where awareness of the issue has remained low, said Lefferts. "In our experience, most consumers have no idea that something that is allowed in the food supply by the FDA could trigger adverse behaviors," she told EHN.
A California State Senate bill introduced in February and backed by the new report would require a similar warning label on foods sold in the state. But it was abruptly withdrawn from the Senate Health Committee on April 28, the day of its scheduled hearing, by sponsor Senator Bob Wieckowski (D-Fremont).
In a press release, Wieckowski said he pulled the bill "to take additional time to brief other senators and make sure they understand the science in the OEHHA report" given that it had been published only 12 days earlier. The bill, which Lefferts said she sees as a wedge for widespread reformulation of dyed foods in the U.S, is now slated to be heard in January 2022.
Widespread Food Dye Exposure
An example of food dyes. jessica / flickr
The FDA last formally reviewed the issue in 2011, when it concluded that a causal link between children's consumption of synthetic color additives and behavioral effects had not been established. At the time the agency also commissioned an exposure assessment of all seven color additives approved for use in food in the U.S.: FD&C Blue No. 1, Blue No. 2, Green No. 3, Red No. 3, Red No. 40, Yellow No. 5, and Yellow No. 6.
The results of this study, later presented in 2014, revealed that between 2007 and 2010, some dyes were consumed on an almost daily basis by up to 98 percent of 2-to-5-year-olds, 95 percent of teenage boys aged 13-18, and 94 percent of the entire U.S. population aged 2 and up.
"Exposure in children affects attention and behavior across the whole spectrum of the population, and it's a widely distributed exposure," Mark Miller, a public health medical officer with OEHHA and one of 13 authors of the report, told EHN. "Overall it means that the impact is subject to being fairly large."
Mechanistic studies reviewed by Miller and the report's other authors reveal that food dyes may impact behavior through a variety of pathways including neurotransmitters, hormones, and oxidative stress. More research is needed on how dyes are absorbed, distributed, and metabolized in the body, they note.
An FDA spokesperson said that the agency had received and was reviewing the report. "The FDA will continue to engage in the scientific and regulatory review of color additives to evaluate their potential impact on various populations, including children, and act when necessary to ensure that the products marketed to consumers are safe and properly labeled," the statement read.
"Parents who wish to limit synthetic color additives in their children's diet may check the food ingredient list on labels, where they are required to be listed."
Reposted with permission from Environmental Health News.
"The feeling that people have towards spiders is not unique," says Marco Isaia, an arachnologist and associate professor at the University of Turin in Italy. "Nightmares, anxieties and fears are very frequent reactions in 'normal' people," he concedes.
Perhaps that's why spiders remain under-represented across the world's endangered-species conservation plans. Average people don't think much about them, relatively few scientists study them, and conservation groups and governments don't act enough to protect them.
That's a major gap in species-protection efforts — one that has wide repercussions. "Efforts in conservation of spiders are particularly meaningful for nature conservation," Isaia points out. Spiders, he says, have enormous ecological value as food for birds and other animals. They're also important to people, both as predators of pest species and as inspiration for medicines and engineering.
And yet they remain neglected.
How bad is the problem? A new paper by Isaia and 18 other experts digs into the conservation status of Europe's 4,154 known spider species and finds that only a few have any protection at the national level. Most have never even been adequately assessed or studied in detail, so we don't know much about their extinction risk or their ecological needs.
Italy, for example, is home to more than 1,700 spider species, but fewer than 450 have had their conservation status assessed and only two have any legal protection in that country.
Greece, meanwhile, has nearly 1,300 spider species within its borders, but scientists have only assessed the conservation needs of 32 of them. None are legally protected.
A jumping spider in Greece. Miltos Gikas / CC BY 2.0
Researchers found the same results — or lack thereof — throughout Europe.
"What surprised us most while assembling the data was the extremely poor level of knowledge about the conservation status, extinction risk and factors threatening the survival of European spider species, despite Europe being one of the most studied regions of the world in terms of biodiversity," says Filippo Milano, the study's lead author and a Ph.D. student in Isaia's research team. "And even when the conservation status of the species was provided, information was often incomplete or out-of-date, resulting in assessments based on poor quality information and high levels of subjectivity."
It's not just individual European nations; the problem is continent-wide. The researchers say just one spider — the endangered Gibraltar funnel-web spider (Macrothele calpeiana) from the Southern Iberian Peninsula — is protected at the European level by the Bern Convention, an international treaty about habitat and species conservation on the continent and some African nations, and European Union Habitats Directive.
Macrothele calpeiana. Gail Hampshire / CC BY 2.0
And of course, this is not unique to Europe; other countries and continents fail to protect arachnids, and for similar reasons.
"Spiders are understudied, underappreciated and under attack by both the climate crisis and humans affecting our environment," says spider expert and science communicator Sebastian Alejandro Echeverri, who was not affiliated with the study. "These are one of the most diverse groups of animals that we don't really think about on a day-to-day basis. There's like 48,000-plus species, but my experience is that most people don't really have a sense of how many are in their area. In the United States, for example, we have just 12 spiders on the endangered species list out of the thousands of species recorded here."
This lack of information or protection at the national level affects international efforts. At the time the research was conducted the IUCN Red List, which includes conservation status assessments for 134,400 species around the world, covered just 301 spider species, eight of which are from Europe. That number has since increased — to all of 318 species from the order Araneae. (And perhaps tellingly, it's worth noting that the Gibraltar funnel-web spider has not currently been assessed for the IUCN Red List.)
The great raft spider (Dolomedes plantarius), listed as vulnerable by the IUCN. Charlie Jackson / CC BY 2.0
The Red List does not grant protections to any species, but it's often used by governments and conservation groups to seek protections on the national or international level.
That dearth of IUCN data seems likely to change, since one of the paper's authors is also the chair of the IUCN Spider and Scorpion Specialist Group, but they have a monumental task ahead of them.
The Web of Borders
As we see with so many other wide-ranging species, a transnational border is often not a spider's friend. The paper identifies several examples of species protected in one country but not its neighbor, despite being found in both places. According to the paper only 17 spider species are protected by conservation legislation in two or more European countries.
"Animals aren't limited by our political lines on a map," notes Echeverri. "You can protect something here, but if that animal's habitat extends past your border and the people next door don't know about it or don't protect its habitat in the same way, it could still be pushed toward extinction even though you're doing your best."
At the same time, cross-border protection can also create problems if legislation is based on out-of-date scientific data. The Gibraltar funnel-web spider — the one species that's listed on the Bern Convention and the EU Habitats Directive — has "protection against all forms of disturbance, capture, keeping, deliberate killing, and damage or destruction of breeding or resting sites," according to the paper. That's essential in its native habitat, but at the same time it's now rapidly spreading through the commercial olive-tree trade and has been spotted in at least four countries outside its range. "As a matter of fact, it seems that the unique spider protected at the European level is considered an alien species in many countries," says Milano.
How Do We Fix This?
Echeverri calls the study "an important call to action." In particular, he points out how it compares different spider assessment and conservation approaches in each country. "This gives people in the IUCN and lawmakers a tool to say, 'hey, this system seems to be working really well, let's take what we can from it that will work great in our country.'"
Isaia notes that they hope this paper spins out a wide-reaching web. "We hope to stimulate environmental government agencies, stakeholders and decision-makers to include spiders in effective conservation strategies and fostering processes that may contribute to the conservation of threatened spider species," he says. Examples, he says, would include "promoting risk assessment procedures for spider species, or including threatened spider species in planning protected areas and biodiversity action plans."
U.S. Fish and Wildlife Service biologist Susan Cameron searches moss mats for the spruce-fir moss spider. G. Peeples / USFWS
But moving forward will require a lot of effort — not to mention some money.
"There's not a lot of funding for naturalists to go out and survey these animals," says Echeverri. "It's this ongoing crisis within science. You don't know a lot about the species, so you don't know who's there. You don't know how many are there. You don't know how they're doing or what habitats they're in, and we need to make our conservation plans based on scientific data. If that data doesn't exist, even if there is a desire to do something for these animals, we can't plan anything because we don't have the fundamentals."
The researchers hope others will take up their mantle to understand and protect spiders. "Highlighting general patterns and identifying the main strengths and weaknesses in biodiversity conservation across Europe is an appropriate starting point to plan achievable solutions focusing on the local context," says Milano. "The same model may be adopted to other geographic regions and may certainly apply to other taxonomic groups."
And maybe, along the way, their work can help inspire people who fear spiders to look at them in a different light — or even to help look for them, like the Map the Spider project that asks citizen scientists to upload locations of the complex webs woven by elusive purse-web spiders.
Who knows, that might even inspire a new generation of arachnologists — a field of scientists who are currently in short supply.
"Focusing on spiders has been a very important choice in my career," Isaia says. "There are those who, like me, see spiders as miracles of the natural evolution. You may study their web, their venom, their bizarre behaviors, the interactions between different species, their role as predators, their amazing taxonomical and functional diversity, their key role in the maintaining ecosystem equilibrium. You may also use them as sources of inspiration in architecture and visual arts. Aren't these good reasons to find them attractive?"
John R. Platt is the editor of The Revelator. An award-winning environmental journalist, his work has appeared in Scientific American, Audubon, Motherboard, and numerous other magazines and publications. His "Extinction Countdown" column has run continuously since 2004 and has covered news and science related to more than 1,000 endangered species. He is a member of the Society of Environmental Journalists and the National Association of Science Writers. John lives on the outskirts of Portland, Ore., where he finds himself surrounded by animals and cartoonists.
Reposted with permission from The Revelator.