j/f 00 wwm · logical services. it is not just rainfall, but groundwater welling up from beneath,...

Reprinted from WORLD WATCH, January/February 2000

Groundwater Shockby Payal Sampat

© 2000 Worldwatch Institute

O R L D WAT C HN S T I T U T EWIW 1776 Massachusetts Ave., NW

Washington, DC 20036www.worldwatch.org

phone: (202) 452-1999 • fax: (202) 296-7365e-mail: [email protected]

10 WORLD•WATCH January/February 2000

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The Mississippi River occupies a mythic place inthe American imagination, in part because it isso huge. At any given moment, on average,

about 2,100 billion liters of water are flowing acrossthe Big Muddy’s broad bottom. If you were to diveabout 35 feet down and lie on that bottom, youmight feel a sense of awe that the whole river was ontop of you. But in one very important sense, you’d becompletely wrong. At any point in time, only 1 per-cent of the water in the Mississippi River system is inthe part of the river that flows downstream to theGulf of Mexico. The other 99 percent lies beneaththe bottom, locked in massive strata of rock and sand.

This is a distinction of enormous consequence.The availability of clean water has come to be recog-nized as perhaps the most critical of all human securi-ty issues facing the world in the next quarter-centu-ry—and what is happening to water buried under thebottoms of rivers, or under our feet, is vastly differentfrom what happens to the “surface” water of rivers,lakes, and streams. New research finds that contraryto popular belief, it is groundwater that is most dan-gerously threatened. Moreover, the Mississippi is notunique in its ratio of surface to underground water;worldwide, 97 percent of the planet’s liquid freshwa-ter is stored in aquifers.

In the early centuries of civilization, surface waterwas the only source we needed to know about.Human population was less than a tenth of one per-cent the size it is now; settlements were on river

banks; and the water was relatively clean. We stillthink of surface water as being the main resource. Soit’s easy to think that the problem of contaminationis mainly one of surface water: it is polluted rivers andstreams that threaten health in times of flood, andthat have made waterborne diseases a major killer ofhumankind. But in the past century, as populationhas almost quadrupled and rivers have become moredepleted and polluted, our dependence on pumpinggroundwater has soared—and as it has, we’ve made aterrible discovery. Contrary to the popular impres-sion that at least the waters from our springs andwells are pure, we’re uncovering a pattern of perva-sive pollution there too. And in these sources, unlikerivers, the pollution is generally irreversible.

This is largely the work of another hidden factor:the rate of groundwater renewal is very slow in com-parison with that of surface water. It’s true that someaquifers recharge fairly quickly, but the average recy-cling time for groundwater is 1,400 years, as opposedto only 20 days for river water. So when we pump outgroundwater, we’re effectively removing it fromaquifers for generations to come. It may evaporateand return to the atmosphere quickly enough, butthe resulting rainfall (most of which falls back intothe oceans) may take centuries to recharge theaquifers once they’ve been depleted. And becausewater in aquifers moves through the Earth withglacial slowness, its pollutants continue to accumu-late. Unlike rivers, which flush themselves into the

GroundwaterShockThe Polluting of the World’s MajorFreshwater Stores

b y P a y a l S a m p a t

Scientists have shown that the worlddeep beneath our feet is essential to thelife above. Ancient myths depicted theUnderworld as a place of damnationand death. Now, the spreading contamination of major aquifersthreatens to turn the myth into a tragic reality.

ILLUSTRATIONS BY PATRICK GNAN

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oceans, aquifers become sinks for pollutants, decadeafter decade—thus further diminishing the amountof clean water they can yield for human use.

Perhaps the largest misconception being explodedby the spreading water crisis is the assumption that theground we stand on—and what lies beneath it—issolid, unchanging, and inert. Just as the advent of cli-mate change has awakened us to the fact that the airover our heads is an arena of enormous forces in themidst of titanic shifts, the water crisis has revealed that,slow-moving though it may be, groundwater is part ofa system of powerful hydrological interactions—between earth, surface water, sky, and sea—that weignore at our peril. A few years ago, reflecting on howhuman activity is beginning to affect climate,Columbia University scientist Wallace Broeckerwarned, “The climate system isan angry beast and we arepoking it with sticks.” Asimilar statement mightnow be made about thesystem under our feet. If wecontinue to drill holes intoit—expecting it to swallow ourwaste and yield freshwater inreturn—we may be toying withan outcome no one could wish.

Valuing Groundwater

For most of human history, groundwa-ter was tapped mainly in arid regions wheresurface water was in short supply. From Egypt toIran, ancient Middle Eastern civilizations usedperiscope-like conduits to funnel spring water frommountain slopes to nearby towns—a technology thatallowed settlement to spread out from the majorrivers. Over the centuries, as populations and crop-land expanded, innovative well-digging techniquesevolved in China, India, and Europe. Water becamesuch a valuable resource that some cultures devel-oped elaborate mythologies imbuing undergroundwater and its seekers with special powers. In medievalEurope, people called water witches or dowsers werebelieved to be able to detect groundwater using aforked stick and mystical insight.

In the second half of the 20th century, the soar-ing demand for water turned the dowsers’ modern-day counterparts into a major industry. Today, majoraquifers are tapped on every continent, and ground-water is the primary source of drinking water formore than 1.5 billion people worldwide (see table,page 12). The aquifer that lies beneath the Huang-Huai-Hai plain in eastern China alone supplies drink-ing water to nearly 160 million people. Asia as awhole relies on its groundwater for nearly one-thirdof its drinking water supply. Some of the largest cities

in the developing world—Jakarta, Dhaka, Lima, andMexico City, among them—depend on aquifers foralmost all their water. And in rural areas, where cen-tralized water supply systems are undeveloped,groundwater is typically the sole source of water.More than 95 percent of the rural U.S. populationdepends on groundwater for drinking.

A principal reason for the explosive rise in ground-water use since 1950 has been a dramatic expansion inirrigated agriculture. In India, the leading country intotal irrigated area and the world’s third largest grainproducer, the number of shallow tubewells used todraw groundwater surged from 3,000 in 1960 to 6million in 1990. While India doubled the amount ofits land irrigated by surface water between 1950 and1985, it increased the area watered by aquifers 113-fold. Today, aquifers supply water to more than half ofIndia’s irrigated land. The United States, with thethird highest irrigated area in the world, uses

groundwater for 43 percent of its irrigated farm-land. Worldwide, irrigation is by far the biggest

drain on freshwater: it accounts for about70 percent of the water we draw from

rivers and wells each year.Other industries have beenexpanding their water use even

faster than agriculture—andgenerating much higher

profits in the process.On average, a ton ofwater used in industrygenerates roughly$14,000 worth of

output—about 70times as much profit as

the same amount of waterused to grow grain. Thus, as

the world has industrialized, sub-stantial amounts of water have been shifted fromfarms to more lucrative factories. Industry’s share oftotal consumption has reached 19 percent and is like-ly to continue rising rapidly. The amount of wateravailable for drinking is thus constrained not only bya limited resource base, but by competition withother, more powerful users.

And as rivers and lakes are stretched to their lim-its—many of them dammed, dried up, or polluted—we’re growing more and more dependent on ground-water for all these uses. In Taiwan, for example, theshare of water supplied by groundwater almost dou-bled from 21 percent in 1983 to over 40 percent in1991. And Bangladesh, which was once almost entire-ly river- and stream-dependent, dug over a millionwells in the 1970s to substitute for its badly pollutedsurface-water supply. Today, almost 90 percent of itspeople use only groundwater for drinking.

Even as our dependence on groundwater increas-

WORLD•WATCH January/February 2000 11


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es, the availability of the resource is becoming morelimited. On almost every continent, many majoraquifers are being drained faster than their natural rateof recharge. Groundwater depletion is most severe inparts of India, China, the United States, North Africa,and the Middle East. Under certain geological condi-tions, groundwater overdraft can cause aquifer sedi-ments to compact, permanently shrinking theaquifer’s storage capacity. This loss can be quite con-siderable, and irreversible. The amount of water stor-age capacity lost because of aquifer compaction inCalifornia’s Central Valley, for example, is equal tomore than 40 percent of the combined storage capac-ity of all human-made reservoirs across the state.

As the competition among factories, farms, andhouseholds intensifies, it’s easy to overlook the extentto which freshwater is also required for essential eco-logical services. It is not just rainfall, but groundwaterwelling up from beneath, that replenishes rivers, lakes,and streams. In a study of 54 streams in different partsof the country, the U.S. Geological Survey (USGS)found that groundwater is the source for more thanhalf the flow, on average. The 492 billion gallons(1.86 cubic kilometers) of water aquifers add to U.S.surface water bodies each day is nearly equal to thedaily flow of the Mississippi. Groundwater providesthe base contribution for the Mississippi, the Niger,the Yangtze, and many more of the world’s greatrivers—some of which would otherwise not be flow-ing year-round. Wetlands, important habitat for birds,fish, and other wildlife, are often largely groundwater-fed, created in places where the water table overflowsto the surface on a constant basis. And while provid-ing surface bodies with enough water to keep themstable, aquifers also help prevent them from flooding:when it rains heavily, aquifers beneath rivers soak upthe excess water, preventing the surface flow from ris-ing too rapidly and overflowing onto neighboring

fields and towns. In tropical Asia, where the hot sea-son can last as long as 9 months, and where monsoonrains can be very intense, this dual hydrological ser-vice is of critical value.

Numerous studies have tracked the extent towhich our increasing demand on water has made it aresource critical to a degree that even gold and oilhave never been. It’s the most valuable thing onEarth. Yet, ironically, it’s the thing most consistentlyoverlooked, and most widely used as a final restingplace for our waste. And, of course, as contaminationspreads, the supplies of usable water get tighter still.

Tracking the Hidden Crisis

In 1940, during the Second World War, the U.S.Department of the Army acquired 70 square kilome-ters of land around Weldon Spring and its neighbor-ing towns near St. Louis, Missouri. Where farmhous-es and barns had been, the Army established theworld’s largest TNT-producing facility. In this sprawl-ing warren of plants, toluene (a component of gaso-line) was treated with nitric acid to produce morethan a million tons of the explosive compound eachday when production was at its peak.

Part of the manufacturing process involved puri-fying the TNT—washing off unwanted “nitroaro-matic” compounds left behind by the chemical reac-tion between the toluene and nitric acid. Over theyears, millions of gallons of this red-colored muckwere generated. Some of it was treated at wastewaterplants, but much of it ran off from the leaky treat-ment facilities into ditches and ravines, and soakedinto the ground. In 1945, when the Army left thesite, soldiers burned down the contaminated build-ings but left the red-tinged soil and the rest of the siteas they were. For decades, the site remained aban-doned and unused.

Then, in 1980, the U.S. EnvironmentalProtection Agency (EPA) launched its“Superfund” program, which required thecleaning up of several sites in the countrythat were contaminated with hazardouswaste. Weldon Spring made it to the list ofsites that were the highest priority forcleanup. The Army Corps of Engineers wasassigned the task, but what the Corps work-ers found baffled them. They expected thesoil and vegetation around the site to becontaminated with the nitroaromatic wastesthat had been discarded there. When theytested the groundwater, however, theyfound that the chemicals were showing upin people’s wells, in towns several milesfrom the site—a possibility that no one hadanticipated, because the original pollutionhad been completely localized. Geologists

Share of Drinking WaterRegion from Groundwater People Served

(percent) (millions)

Asia-Pacific 32 1,000 to 1,200Europe 75 200 to 500Latin America 29 150United States 51 135Australia 15 3Africa NA NA

World 1,500 to 2,000

Sources: UNEP, OECD, FAO, U.S. EPA, Australian EPA.

Groundwater as a Share of Drinking Water Use, by Region


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determined that there was an enormous plume ofcontamination in the water below the TNT factory—a plume that over the previous 35 years had flowedthrough fissures in the limestone rock to other partsof the aquifer.

The Weldon Spring story may sound like anexceptional case of clumsy planning combined with aparticularly vulnerable geological structure. But infact there is nothing exceptional about it all. Acrossthe United States, as well as in parts of Europe, Asia,and Latin America, human activities are sending mas-sive quantities of chemicals and pollutants intogroundwater. This isn’t entirely new, of course; thesubterranean world has always been a receptacle forwhatever we need to dispose of—whether oursewage, our garbage, or our dead. But the enormousvolumes of waste we now send underground, and thedeadly mixes of chemicals involved, have createdproblems never before imagined.

What Weldon Spring shows is that we can’t alwaysanticipate where the pollution is going to turn up inour water, or how long it will be from the time it wasdeposited until it reappears. Because groundwatertypically moves very slowly—at a speed of less than afoot a day, in some cases—damage done to aquifersmay not show up for decades. In many parts of theworld, we are only just beginning to discover conta-mination caused by practices of 30 or 40 years ago.Some of the most egregious cases of aquifer contam-ination now being unearthed date back to Cold Warera nuclear testing and weapons-making, for exam-ple. And once it gets into groundwater, the pollutionusually persists: the enormous volume, inaccessibility,and slow rate at which groundwater moves makeaquifers virtually impossible to purify.

As this covert crisis unfolds, we are barely begin-ning to understand its dimensions. Few countriestrack the health of their aquifers—their enormous sizeand remoteness make them extremely expensive tomonitor. As the new century begins, even hydrogeol-ogists and health officials have only a hazy impressionof the likely extent of groundwater damage in differ-ent parts of the world. Nonetheless, given the data wenow have, it is possible to sketch a rough map of theregions affected, and the principal threats they face(see map, page 18, and table, page 21).

The Filter that Failed:Pesticides in Your Water

Pesticides are designed to kill. The first syntheticpesticides were introduced in the 1940s, but it tookseveral decades of increasingly heavy use before itbecame apparent that these chemicals were injuringnon-target organisms—including humans. One rea-son for the delay was that some groups of pesticides,such as organochlorines, usually have little effect until

they bioaccumulate. Their concentration in living tis-sue increases as they move up the food chain. Soeventually, the top predators—birds of prey, forexample—may end up carrying a disproportionatelyhigh burden of the toxin. But bioaccumulation takestime, and it may take still more time before theeffects are discovered. In cases where reproductivesystems are affected, the aftermath of this chemicalaccumulation may not show up for a generation.

Even when the health concerns of some pesticideswere recognized in the 1960s, it was easily assumedthat the real dangers lay in the dispersal of these chem-icals among animals and plants—not deep under-ground. It was assumed that very little pesticide wouldleach below the upper layers of soil, and that if it did,it would be degraded before it could get any deeper.Soil, after all, is known to be a natural filter, whichpurifies water as it trickles through. It was thoughtthat industrial or agricultural chemicals, like such nat-ural contaminants as rock dust, or leaf mold, would befiltered out as the water percolated through the soil.

But over the past 35 years, this seemingly safeassumption has proved mistaken. Cases of extensivepesticide contamination of groundwater have cometo light in farming regions of the United States,Western Europe, Latin America, and South Asia.What we now know is that pesticides not only leachinto aquifers, but sometimes remain there long afterthe chemical is no longer used. DDT, for instance, isstill found in U.S. waters even though its use wasbanned 30 years ago. In the San Joaquin Valley ofCalifornia, the soil fumigant DBCP (dibromochloro-propane), which was used intensively in fruitorchards before it was banned in 1977, still lurks inthe region’s water supplies. Of 4,507 wells sampledby the USGS between 1971 and 1988, nearly a thirdhad DBCP levels that were at least 10 times higherthan allowed by the current drinking water standard.

In places where organochlorines are still widelyused, the risks continue to mount. After half a centu-ry of spraying in the eastern Indian states of WestBengal and Bihar, for example, the Central PollutionControl Board found DDT in groundwater at levelsas high as 4,500 micrograms per liter—several thou-sand times higher than what is considered a safe dose.

The amount of chemical that reaches groundwaterdepends on the amount used above ground, the geol-ogy of the region, and the characteristics of the pesti-cide itself. In some parts of the midwestern UnitedStates, for example, although pesticides are used inten-sively, the impermeable soils of the region make it dif-ficult for the chemicals to percolate underground. Thefissured aquifers of southern Arizona, Florida, Maine,and southern California, on the other hand, are veryvulnerable to pollution—and these too are placeswhere pesticides are applied in large quantities.

Pesticides are often found in combination, because

most farms use a range of toxins to destroy differentkinds of insects, fungi, and plant diseases. The USGSdetected two or more pesticides in groundwater atnearly a quarter of the sites sampled in its NationalWater Quality Assessment between 1993 and 1995. Inthe Central Columbia Plateau aquifer, which extendsover the states of Washington and Idaho, more thantwo-thirds of water samples contained multiple pesti-cides. Scientists aren’t entirely sure what happens whenthese chemicals and their various metabolites cometogether. We don’t even have standards for the manyhundred individual pesticides in use—the EPA hasdrinking water standards for just 33 of these com-pounds—to say nothing of the infinite variety of toxicblends now trickling into the groundwater.

While the most direct impacts may be on thewater we drink, there is also concern about whatoccurs when the pesticide-laden water below farm-land is pumped back up for irrigation. One apparentconsequence is a reduction in crop yields.

In 1990, the now-defunct U.S. Office ofTechnology Assess-

ment reported thatherbicides in

shallow groundwater had the effect of “pruning”crop roots, thereby retarding plant growth.

From Green Revolution to BlueBaby: the Slow Creep of Nitrogen

Since the early 1950s, farmers all over the worldhave stepped up their use of nitrogen fertilizers.Global fertilizer use has grown ninefold in that time.But the larger doses of nutrients often can’t be fullyutilized by plants. A study conducted over a 140,000square kilometer region of Northern China, forexample, found that crops used on average only 40percent of the nitrogen that was applied. An almostidentical degree of waste was found in Sri Lanka.Much of the excess fertilizer dissolves in irrigationwater, eventually trickling through the soil intounderlying aquifers.

Joining the excess chemical fertilizer from farmcrops is the organic waste generated by farm animals,and the sewage produced by cities. Livestock wasteforms a particularly potent tributary to the stream ofexcess nutrients flowing into the environment,because of its enormous volume. In the UnitedStates, farm animals produce 130 times as muchwaste as the country’s people do—with the resultthat millions of tons of cow and pig feces are washedinto streams and rivers, and some of the nitrogen

they carry ends up in groundwater. To this Augeanburden can be added the innumerable leaks and over-flows from urban sewage systems, the fertilizer runofffrom suburban lawns, golf courses, and landscaping,and the nitrates leaking (along with other pollutants)from landfills.

There is very little historical information availableabout trends in the pollution of aquifers. But severalstudies show that nitrate concentrations haveincreased as fertilizer applications and population sizehave grown. In California’s San Joaquin-TulareValley, for instance, nitrate levels in groundwaterincreased 2.5 times between the 1950s and 1980s—a period in which fertilizer inputs grew six-fold.Levels in Danish groundwater have nearly tripledsince the 1940s. As with pesticides, the aftermath ofthis multi-sided assault of excess nutrients has onlyrecently begun to become visible, in part because ofthe slow speed at which nitrate moves underground.

What happens when nitrates get into drinkingwater? Consumed in high concentrations—atlevels above 10 milligrams (mg) per liter, but

usually on the order of 100 mg/liter—they cancause infant methemoglobinemia, or so-called

blue-baby syndrome. Because of their low gastricacidity, infant digestive systems convert nitrate tonitrite, which blocks the oxygen-carrying capacityof a baby’s blood, causing suffocation and death.Since 1945, about 3,000 cases have been reported

worldwide—nearly half of them in Hungary, whereprivate wells have particularly high concentrations ofnitrates. Ruminant livestock such as goats, sheep, andcows, are vulnerable to methemoglobinemia in muchthe same way infants are, because their digestive sys-tems also quickly convert nitrate to nitrite. Nitrates arealso implicated in digestive tract cancers, although theepidemiological link is still uncertain.

In cropland, nitrate pollution of groundwater canhave a paradoxical effect. Too much nitrate can weak-en plants’ immune systems, making them more vul-nerable to pests and disease. So when nitrate-ladengroundwater is used to irrigate crops that are alsobeing fertilized, the net effect may be to reduce,rather than to increase production. This kind of over-fertilizing makes wheat more susceptible to wheatrust, for example, and it makes pear trees more vul-nerable to fire blight.

In assembling studies of groundwater fromaround the world, we have found that nitrate pollu-tion is pervasive—but has become particularly severein the places where human population—and thedemand for high food productivity—is most concen-trated. In the northern Chinese counties of Beijing,Tianjin, Hebei, and Shandong, nitrate concentrationsin groundwater exceeded 50 mg/liter in more thanhalf of the locations studied. (The World HealthOrganization [WHO] drinking water guideline is 10mg/liter.) In some places, the concentration had

risen as high as 300 mg/liter. Since then, these levelsmay have increased, as fertilizer applications haveescalated since the tests were carried out in 1995 andwill likely increase even more as China’s population(and demand for food) swells, and as more farmlandis lost to urbanization, industrial development, nutri-ent depletion, and erosion.

Reports from other regions show similar results.The USGS found that about 15 percent of shallowgroundwater sampled below agricultural and urbanareas in the United States had nitrate concentrationshigher than the 10 mg/liter guideline. In Sri Lanka,79 percent of wells sampled by the British GeologicalSurvey had nitrate levels that exceeded this guideline.Some 56 percent of wells tested in the Yucatán penin-sula in Mexico had levels above 45 mg/liter. And theEuropean Topic Centre on Inland Waters found thatin Romania and Moldova, more than 35 percent ofthe sites sampled had nitrate concentrations higherthan 50 mg/liter.

From Tank of Gas to DrinkingGlass: the Pervasiveness ofPetrochemicals

Drive through any part of the UnitedStates, and you’ll probably pass more gas sta-tions than schools or churches. As you pullinto a station to fill up, it may not occur toyou that you’re parked over one of themost pervasive threats to ground-

water: an underground storage tank (UST) for petro-leum. Many of these tanks were installed two or threedecades ago and, having been left in place long pasttheir expected lifetimes, have rusted through inplaces—allowing a steady leakage of gasoline into theground. Because they’re underground, they’re expen-sive to dig up and repair, so the leakage in some casescontinues for years.

Petroleum and its associated chemicals—benzene,toluene, and gasoline additives such as MTBE—con-stitute the most common category of groundwatercontaminant found in aquifers in the United States.Many of these chemicals are also known or suspectedto be cancer-causing. In 1998, the EPA found thatover 100,000 commercially owned petroleum USTswere leaking, of which close to 18,000 are known tohave contaminated groundwater. In Texas, 223 of254 counties report leaky USTs, resulting in a silentdisaster that, according to the EPA, “has affected, orhas the potential to affect, virtually every major andminor aquifer in the state.” Household tanks, whichstore home heating oil, are a problem as well.


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Although the household tanks aren’t subject to thesame regulations and inspections as commercial ones,the EPA says they are “undoubtedly leaking.”Outside the United States, the world’s ubiquitouspetroleum storage tanks are even less monitored, butspot tests suggest that the threat of leakage isomnipresent in the industrialized world. In 1993,petroleum giant Shell reported that a third of its1,100 gas stations in the United Kingdom wereknown to have contaminated soil and groundwater.Another example comes from the eastern Kazakhtown of Semipalatinsk, where 6,460 tons of kerosenehave collected in an aquifer under a military airport,seriously threatening the region’s water supplies.

The widespread presence of petrochemicals ingroundwater constitutes a kind of global malignancy,the danger of which has grown unobtrusively becausethere is such a great distance between cause andeffect. An underground tank, for example, may takeyears to rust; it probably won’t begin leaking untillong after the people who bought it and installed ithave left their jobs. Even after it begins to leak, it maytake several more years before appreciable concentra-tions of chemicals appear in the aquifer—and it willlikely be years beyond that before any health effectsshow up in the local population. By then, the trailmay be decades old. So it’s quite possible that anycancers occurring today as a result of leaking USTsmight originate from tanks that were installed half acentury ago. At that time, there were gas tanks suffi-cient to fuel 53 million cars in the world; today thereare enough to fuel almost 10 times that number.

From Sediment to Solute: theEmerging Threat of NaturalContaminants

In the early 1990s, several villagers living nearIndia’s West Bengal border with Bangladesh beganto complain of skin sores that wouldn’t go away. Aresearcher at Calcutta’s Jadavpur University,Dipankar Chakraborti, recognized the lesions imme-diately as early symptoms of chronic arsenic poison-ing. In later stages, the disease can lead to gangrene,skin cancer, damage to vital organs, and eventually,death. In the months that followed, Chakrabortibegan to get letters from doctors and hospitals inBangladesh, who were seeing streams of patients withsimilar symptoms. By 1995, it was clear that thecountry faced a crisis of untold proportions, and thatthe source of the poisoning was water from tube-wells, from which 90 percent of the country gets itsdrinking water.

Experts estimate that today, arsenic in drinkingwater could threaten the health of 20 to 60 millionBangladeshis—up to half the country’s population—and another 6 to 30 million people in West Bengal

As many as 1 million wells in the region may be con-taminated with the heavy metal at levels between 5and 100 times the WHO drinking water guideline of0.01 mg/liter.

How did the arsenic get into groundwater? Untilthe early 1970s, rivers and ponds supplied most ofBangladesh’s drinking water. Concerned about therisks of water-borne disease, the WHO and interna-tional aid agencies launched a well-drilling programto tap groundwater instead. However, the agencies,not aware that soils of the Ganges aquifers are natu-rally rich in arsenic, didn’t test the sediment beforedrilling tubewells. Because the effects of chronicarsenic poisoning can take up to 15 years to appear,the epidemic was not addressed until it was wellunder way.

Scientists are still debating what chemical reac-tions released the arsenic from the mineral matrix inwhich it is naturally bound up. Some theories impli-cate human activities. One hypothesis is that as waterwas pumped out of the wells, atmospheric oxygenentered the aquifer, oxidizing the iron pyrite sedi-ments, and causing the arsenic to dissolve. AnOctober 1999 article in the scientific journal Natureby geologists from the Indian Institute ofTechnology suggests that phosphates from fertilizerrunoff and decaying organic matter may have playeda role. The nutrient might have spurred the growthof soil microorganisms, which helped to loosenarsenic from sediments.

Salt is another naturally occurring groundwaterpollutant that is introduced by human activity.Normally, water in coastal aquifers empties into thesea. But when too much water is pumped out ofthese aquifers, the process is reversed: seawater movesinland and enters the aquifer. Because of its high saltcontent, just 2 percent of seawater mixed with fresh-water makes the water unusable for drinking or irri-gation. And once salinized, a freshwater aquifer canremain contaminated for a very long time. Brackishaquifers often have to be abandoned because treat-ment can be very expensive.

In Manila, where water levels have fallen 50 to 80meters because of overdraft, seawater has flowed asfar as 5 kilometers into the Guadalupe aquifer thatlies below the city. Saltwater has traveled several kilo-meters inland into aquifers beneath Jakarta andMadras, and in parts of the U.S. state of Florida.Saltwater intrusion is also a serious problem onislands such as the Maldives and Cyprus, which arevery dependent on aquifers for water supply.

Fluoride is another natural contaminant thatthreatens millions in parts of Asia. Aquifers in the drierregions of western India, northern China, and parts ofThailand and Sri Lanka are naturally rich in fluoridedeposits. Fluoride is an essential nutrient for bone anddental health, but when consumed in high concentra-


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tions, it can lead to crippling damage to the neck andback, and to a range of dental problems. The WHOestimates that 70 million people in northern China,and 30 million in northwestern India are drinkingwater with high fluoride levels.

A Chemical Soup

With just over a million residents, Ludhiana is thelargest city in Punjab, India’s breadbasket state. It isalso an important industrial town, known for its tex-tile factories, electroplating industries, and metalfoundries. Although the city is entirely dependent ongroundwater, its wells are now so polluted with indus-trial and urban wastes that the water is no longer safeto drink. Samples show high levels of cyanide, cadmi-um, lead, and pesticides. “Ludhiana City’s groundwa-ter is just short of poison,” laments a senior official atIndia’s Central Ground Water Board.

Like Ludhiana’s residents, more than a third ofthe planet’s people live and work in densely settledcities, which occupy just 2 percent of the Earth’s landarea. With the labor force thus concentrated, facto-ries and other centers of employment also group

together around the same urban areas. Aquifers inthese areas are beginning to mirror the increasingdensity and diversity of the human activity abovethem. Whereas the pollutants emanating from hogfarms or copper mines may be quite predictable, thewaste streams flowing into the water under cities con-tain a witch’s brew of contaminants.

Ironically, a major factor in such contamination isthat in most places people have learned to dispose ofwaste—to remove it from sight and smell—so effec-tively that it is easy to forget that the Earth is a closedecological system in which nothing permanently dis-appears. The methods normally used to concealgarbage and other waste—landfills, septic tanks, andsewers—become the major conduits of chemical pol-lution of groundwater. In the United States, business-es drain almost 2 million kilograms of assorted chem-icals into septic systems each year, contaminating thedrinking water of 1.3 million people. In many parts ofthe developing world, factories still dump their liquideffluents onto the ground and wait for it to disappear.In the Bolivian city of Santa Cruz, for example, a shal-low aquifer that is the city’s main water source has hadto soak up the brew of sulfates, nitrates, and chlorides

Russia

Hungary

Denmark

Netherlands

India

China

Thailand

Sri LankaBangladesh

Philippines

Japan

Australia

United Kingdom

Kazahkstan

S

S

F

F

As

SS

F

Pb

N

N

Pb

Pb

Spain

NFrance

S

Pb

PbAs

S

AsTaiwan

NGermany

N N

S PbGroundwater Contamination HotspotsThis is a rough regional portrait of aquifer pollution as described in thecurrent scientific literature. The full extent of contamination is not known,since most of the world’s aquifers have yet to be tested.

No data available


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dumped over it. And even protected landfills can be apotent source of aquifer pollution: the EPA found thata quarter of the landfills in the U.S. state of Maine, forexample, had contaminated groundwater.

In industrial countries, waste that is too haz-ardous to landfill is routinely buried in undergroundtanks. But as these caskets age, like gasoline tanks,they eventually spring leaks. In California’s SiliconValley, where electronics industries store assortedwaste solvents in underground tanks, local ground-water authorities found that 85 percent of the tanksthey inspected had leaks. Silicon Valley now has moreSuperfund sites—most of them affecting groundwa-ter—than any other area its size in the country. And60 percent of the United States’ liquid hazardouswaste—34 billion liters of solvents, heavy metals, andradioactive materials—is directly injected into theground. Although the effluents are injected belowthe deepest source of drinking water, some of thesewastes have entered aquifers used for water suppliesin parts of Florida, Texas, Ohio, and Oklahoma.

Shenyang, China, and Jaipur, India, are among thescores of cities in the developing world that have hadto seek out alternate supplies of water because their

groundwater has become unusable. SantaCruz has also struggled to find cleanwater. But as it has sunk deeper wells inpursuit of pure supplies, the effluent hastraveled deeper into the aquifer to replacethe water pumped out of it. In placeswhere alternate supplies aren’t easilyavailable, utilities will have to resort toincreasingly elaborate filtration set-upsto make the water safe for drinking. Inheavily contaminated areas, hundreds ofdifferent filters may be necessary. At pre-sent, utilities in the U.S. Midwest spend$400 million each year to treat water forjust one chemical—atrazine, the mostcommonly detected pesticide in U.S.groundwater. When chemicals are foundin unpredictable mixtures, rather thandiscretely, providing safe water maybecome even more expensive.

One Body, Many Wounds

The various incidents of aquifer pol-lution described may seem isolated. Agroup of wells in northern China havenitrate problems; another lot in theUnited Kingdom are laced with benzene.In each place it might seem that theproblem is local and can be contained.But put them together, and you begin tosee a bigger picture emerging. Perhapsmost worrisome is that we’ve discovered

as much damage as we have, despite the very limitedmonitoring and testing of underground water. Andbecause of the time-lags involved—and given ourhigh levels of chemical use and waste generation inrecent decades—what’s still to come may bring evenmore surprises.

Some of the greatest shocks may be felt in placeswhere chemical use and disposal has climbed in thelast few decades, and where the most basic measuresto shield groundwater have not been taken. In India,for example, the Central Pollution Control Board(CPCB) surveyed 22 major industrial zones andfound that groundwater in every one of them wasunfit for drinking. When asked about these findings,CPCB chairman D.K. Biswas remarked, “The resultis frightening, and it is my belief that we will getmore shocks in the future.”

Jack Barbash, an environmental chemist at theU.S. Geological Survey, points out that we may notneed to wait for expensive tests to alert us to what toexpect in our groundwater. “If you want to knowwhat you’re likely to find in aquifers near Shanghai orCalcutta, just look at what’s used above ground,” hesays. “If you’ve been applying DDT to a field for 20

United States

Mexico

BrazilBolivia

Costa Rica

As

PbN

Pb

N

N

NS

S

N

N

NKEY

AsF

S

Radioactivewaste

Lead and otherheavy metals

NPb

Arsenic

Fluorides

Nitrates

Pesticides

Solvents

Salts

Petrochemicals


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years, for example, that’s one of the chemicals you’relikely to find in the underlying groundwater.” Thefull consequences of today’s chemical-dependent andwaste-producing economies may not become appar-ent for another generation, but Barbash and otherscientists are beginning to get a sense of just howserious those consequences are likely to be if presentconsumption and disposal practices continue.

Changing Course

Farmers in California’s San Joaquin Valley begantapping the area’s seemingly boundless groundwaterstore in the late-nineteenth century. By 1912, theaquifer was so depleted that the water table had fall-en by as much as 400 feet in some places. But thefarmers continued to tap the resource to keep upwith demand for their produce. Over time, the dehy-dration of the aquifer caused its clay soil to shrink,and the ground began to sink—or as geologists putit, to “subside.” In some parts of the valley, theground has subsided as much as 29 feet—crackingfoundations, canals, and aqueducts.

When the San Joaquin farmers could no longerpump enough groundwater to meet their irrigationdemands, they began to bring in water from thenorthern part of the state via the California Aqueduct.The imported water seeped into the compactedaquifer, which was not able to hold all of the incomingflow. The water table then rose to an abnormally highlevel, dissolving salts and minerals in soils that had notbeen previously submerged. The salty groundwater,welling up from below, began to poison crop roots. Inresponse, the farmers installed drains under irrigatedfields—designed to capture the excess water and divertit to rivers and reservoirs in the valley so that it would-n’t evaporate and leave its salts in the soil.

But the farmers didn’t realize that the rocks andsoils of the region contained substantial amounts ofthe mineral selenium, which is toxic at high doses.Some of the selenium leached into the drainagewater, which was routed to the region’s wetlands. Itwasn’t until the mid-1980s that the aftermath of thissolution became apparent: ecologists noticed thatthousands of waterfowl in the nearby KestersonReservoir were dying of selenium poisoning.

Hydrological systems are not easy to outmaneu-ver, and the San Joaquin farmers’ experience serves asa kind of cautionary tale. Each of their stopgap solu-tions temporarily took care of an immediate obstacle,but led to a longer-term problem more severe thanthe original one. “Human understanding has laggedone step behind the inflexible realities governing theaquifer system,” observes USGS hydrologist FrankChapelle.

Around the world, human responses to aquiferpollution thus far have essentially reenacted the San

Joaquin Valley farmers’ well-meaning but inadequateapproach. In many places, various authorities andindustries have fought back the contamination leakby leak, or chemical by chemical—only to find thatthe individual fixes simply don’t add up. As we linelandfills to reduce leakage, for instance, tons of pesti-cide may be running off nearby farms and intoaquifers. As we mend holes in underground gastanks, acid from mines may be seeping into ground-water. Clearly, it’s essential to control the damagewe’ve already inflicted, and to protect communitiesand ecosystems from the poisoned fallout. But givenwhat we already know—that damage done to aquifersis mostly irreversible, that it can take years beforegroundwater pollution reveals itself, that chemicalsreact synergistically, and often in unanticipatedways—it’s now clear that a patchwork response isn’tgoing to be effective. Given how much damage thispollution inflicts on public health, the environment,and the economy once it gets into the water, it’s crit-ical that emphasis be shifted from filtering out toxinsto not using them in the first place. Andrew Skinner,who heads the International Association ofHydrogeologists, puts it this way: “Prevention is theonly credible strategy.”

To do this requires looking not just at individualfactories, gas stations, cornfields, and dry cleaningplants, but at the whole social, industrial, and agri-cultural systems of which these businesses are a part.The ecological untenability of these systems is what’sreally poisoning the world’s water. It is the predomi-nant system of high-input agriculture, for example,that not only shrinks biodiversity with its vast mono-cultures, but also overwhelms the land—and theunderlying water—with its massive applications ofagricultural chemicals. It’s the system of car-domi-nated, geographically expanding cities that not onlygenerates unsustainable amounts of climate-disrupt-ing greenhouse gases and acid rain-causing air pollu-tants, but also overwhelms aquifers and soils withpetrochemicals, heavy metals, and sewage. An ade-quate response will require a thorough overhaul ofeach of these systems.

Begin with industrial agriculture. Farm runoff is aleading cause of groundwater pollution in many partsof Europe, the United States, China, and India.Lessening its impact calls for adopting practices thatsharply reduce this runoff—or, better still, thatrequire far smaller inputs to begin with. In mostplaces, current practices are excessively wasteful. InColombia, for example, growers spray flowers with asmuch as 6,000 liters of pesticide per hectare. InBrazil, orchards get almost 10,000 liters per hectare.Experts at the U.N. Food and Agricultural Organi-zation say that with modified application techniques,these chemicals could be applied at one-tenth thoseamounts and still be effective. But while using more


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efficient pesticide applications would constitute amajor improvement, there is also the possibility ofreorienting agriculture to use very little synthetic pes-ticide at all. Recent studies suggest that farms canmaintain high yields while using little or no syntheticinput. One decade-long investigation by the RodaleInstitute in Pennsylvania, for example, compared tra-ditional manure and legume-based cropping systemswhich used no synthetic fertilizer or pesticides, witha conventional, high-intensity system. All three fieldswere planted with maize and soybeans. The

researchers found that the traditional systemsretained more soil organic matter and nitrogen—indicators of soil fertility—and leached 60 percentless nitrate than the conventional system. Althoughorganic fertilizer (like its synthetic counterpart) istypically a potent source of nitrate, the rotations ofdiverse legumes and grasses helped fix and retainnitrogen in the soil. Yields for the maize and soybeancrops differed by less than 1 percent between thethree cropping systems over the 10-year period.

In industrial settings, building “closed-loop” pro-

Health and Ecosystem EffectsThreat Sources at High Concentrations Principal Regions Affected

Pesticides Runoff from farms, Organochlorines linked to United States, Easternbackyards, golf courses; reproductive and endocrine damage Europe, China, India.landfill leaks. in wildlife; organophosphates and

carbamates linked to nervoussystem damage and cancers.

Nitrates Fertilizer runoff; manure Restricts amount of oxygen reaching Midwestern and mid-Atlanticfrom livestock operations; brain, which can cause death in United States, North Chinaseptic systems. infants (“blue-baby syndrome”); Plain, Western Europe,

linked to digestive tract cancers. Northern India.Causes algal blooms and eutro-phication in surface waters.

Petro- Underground petroleum Benzene and other petrochemicals United States, Unitedchemicals storage tanks. can be cancer-causing even at low Kingdom, parts of former

exposure. Soviet Union.

Chlorinated Effluents from metals and Linked to reproductive disorders and Western United States,Solvents plastics degreasing; fabric some cancers. industrial zones in East Asia.

cleaning, electronics andaircraft manufacture.

Arsenic Naturally occurring; possibly Nervous system and liver damage; Bangladesh, Eastern India,exacerbated by over- skin cancers. Nepal, Taiwan.pumping aquifers and byphosphorus from fertilizers.

Other Heavy Mining waste and tailings; Nervous system and kidney damage; United States, CentralMetals landfills; hazardous waste metabolic disruption. America and northeastern

dumps. South America, EasternEurope.

Fluoride Naturally occurring. Dental problems; crippling spinal and Northern China, Westernbone damage. India; parts of Sri Lanka

and Thailand.

Salts Seawater intrusion; de-icing Freshwater unusable for drinking Coastal China and India,salt for roads. or irrigation. Gulf coasts of Mexico and

Florida, Australia,Philippines.

Major sources: European Environmental Agency, USGS, British Geological Survey.

Some Major Threats to Groundwater


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duction and consumption systems can help slash thequantities of waste that factories and cities send tolandfills, sewers, and dumps—thus protectingaquifers from leaking pollutants. In places as far-rang-ing as Tennessee, Fiji, Namibia, and Denmark, envi-ronmentally conscious investors have begun to build“industrial symbiosis” parks in which the unusablewastes from one firm become the input for another.An industrial park in Kalundborg, Denmark divertsmore than 1.3 million tons of effluent from landfillsand septic systems each year, while preventing some135,000 tons of carbon and sulfur from leaking intothe atmosphere. Households, too, can become a partof this systemic change by reusing and repairingproducts. In a campaign organized by the GlobalAction Plan for the Earth, an international non-governmental organization, thoughtful consumptionhabits have enabled some 60,000 households in theUnited States and Europe to reduce their waste by 42percent and their water use by 25 percent.

As it becomes clearer to decisionmakers that themost serious threats to human security are no longerthose of military attack but of pervasive environmen-tal and social decline, experts worry about the diffi-culty of mustering sufficient political will to bringabout the kinds of systemic—and therefore revolu-tionary—changes in human life necessary to turn thetide in time. In confronting the now heavily docu-mented assaults of climate change and biodiversityloss, leaders seem on one hand paralyzed by how bleakthe big picture appears to be—and on the other handtoo easily drawn into denial or delay by the seeminglack of immediate consequences of such delay. Butprotecting aquifers may provide a more immediateincentive for change, if only because it simply may notbe possible to live with contaminated groundwater foras long as we could make do with a gradually moreirritable climate or polluted air or impoverishedwildlife. Although we’ve damaged portions of someaquifers to the point of no return, scientists believethat a large part of the resource still remains pure—forthe moment. That’s not likely to remain the case if wecontinue to depend on simply stepping up the presentreactive tactics of cleaning up more of the chemicalspills, replacing more of the leaking gasoline tanks,placing more plastic liners under landfills, or issuing

more fines to careless hog farms and copper mines. Tosave the water in time requires the same fundamentalrestructuring of the global economy as does the stabi-lizing of the climate and biosphere as a whole—therapid transition from a resource-depleting, oil- andcoal-fueled, high-input industrial and agriculturaleconomy to one that is based on renewable energy,compact cities, and a very light human footprint.We’ve been slow to come to grips with this, but it maybe our thirst that finally makes us act.

“Heaven is Under Our Feet”

Throughout human history, people have fearedthat the skies would be the source of great destruc-tion. During the Cold War, industrial nations fearednuclear attack from above, and spent vast amounts oftheir wealth to avert it. Now some of that fear hasshifted to the threats of atmospheric climate change:of increasing ultraviolet radiation through the ozonehole, and the rising intensity of global warming-dri-ven hurricanes and typhoons. Yet, all the while, as theworldwide pollution of aquifers now reveals, we’vebeen slowly poisoning ourselves from beneath. Whatlies under terra firma may, in fact, be of as much con-cern as what happens in the firmament above.

The ancient Greeks created an elaborate mythol-ogy about the Underworld, or Hades, which theydescribed as a dismal, lifeless place completely lackingthe abundant fertility of the world above. Science andhuman experience have taught us differently.Hydrologists now know that healthy aquifers areessential to the life above ground—that they play avital role not just in providing water to drink, but inreplenishing rivers and wetlands and, through theirultimate effects on rainfall and climate, in nurturingthe life of the land and air as well. But ironically, ourneglectful actions now threaten to make the Greekmyth a reality after all. To avert that threat now willrequire taking to heart what the hydrologists havefound. As Henry David Thoreau observed a century-and-a-half ago, “Heaven is under our feet, as well asover our heads.”

Payal Sampat is a staff researcher at the WorldwatchInstitute.

Francis H. Chapelle, The Hidden Sea: Ground Water, Springs, and Wells (Tucson, AZ: Geoscience Press, Inc., 1997).

U.N. Environment Programme, Groundwater: A Threatened Resource (Nairobi: 1996).

European Environmental Agency, Groundwater Quality and Quantity in Europe (Copenhagen: 1999).

U.S. Geological Survey, The Quality of Our Nation’s Waters—Nutrients and Pesticides (Reston, VA: 1999).

British Geological Survey et al., Characterisation and Assessment of Groundwater Quality Concerns in Asia-PacificRegion (Oxfordshire, UK: 1996).

A Few Key Sources

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