The Hidden Freshwater Crisis
Toxic chemicals are contaminating groundwater on every inhabited continent, endangering the world's most valuable supplies of freshwater, reports a new study from the Worldwatch Institute, a Washington, DC-based research organization. This first global survey of groundwater pollution shows that a toxic brew of pesticides, nitrogen fertilizers, industrial chemicals, and heavy metals is fouling groundwater everywhere, and that the damage is often worst in the very places where people most need water.
"Groundwater contamination is an irreversible act that will deprive future generations of one of life's basic resources," said Payal Sampat, author of Deep Trouble: The Hidden Threat of Groundwater Pollution. "In the next 50 years, an additional 3 billion people are expected to inhabit the Earth, creating even more demand for water for drinking, irrigation, and industry. But we're polluting our cheapest and most easily accessible supply of water. Most groundwater is still pristine, but unless we take immediate action, clean groundwater will not be there when we need it."
Groundwater is an essential resource for sustaining civilization. Some 97 percent of the planet's liquid freshwater is stored in underground aquifers. Nearly one third of all humanity relies almost exclusively on groundwater for drinking, including the residents of some of the largest cities in the developing world, such as Jakarta, Dhaka, Lima, and Mexico City. Almost 99 percent of the rural U.S. population, and 80 percent of India's villagers, depend on groundwater for drinking.
Groundwater irrigates some of the world's most productive cropland. More than half of irrigated farmland in India, and 43 percent in the United States, are watered by groundwater. Irrigation already accounts for about two thirds of water use worldwide. As rivers and lakes are dammed, dried up, or polluted, and as food demand grows in the next 50 years, farmers will become increasingly dependent on groundwater for irrigation.
Groundwater also plays a key ecological role by replenishing rivers, streams, and wetlands. It provides much of the flow for the Mississippi, the Niger, the Yangtze, and many other great rivers-some of which would otherwise not run year-round.
Groundwater contamination is already widespread:
• In the late 1990s, India's Central Pollution Control Board found that groundwater was unfit for drinking in all 22 major industrial zones it surveyed.
• One third of the wells tested in California's San Joaquin Valley in 1988 contained the pesticide DBCP at levels 10 times higher than the maximum allowed for drinking water-more than a decade after its use was banned.
• The U.S. Environmental Protection Agency (EPA) estimates that about 100,000 gasoline storage tanks are leaking chemicals into groundwater. In Santa Monica, California, wells supplying half the city's water have been closed because of dangerously high levels of the gasoline additive MTBE.
• In the northern Chinese provinces of Beijing, Tianjin, Hebei, and Shandong, nitrate concentrations in groundwater exceeded the health guideline in more than half of the locations studied in 1995.
"One of the most disturbing aspects of the problem is that groundwater pollution is essentially permanent," said Sampat. Water recycles extremely slowly underground, too slowly to flush out or dilute toxic chemicals. Water that enters an aquifer remains there for an average of 1,400 years, compared to only 16 days for rivers. Thus Londoners, for example, may be drinking water that fell as rain as long ago as the last Ice Age.
The urgency of preventing groundwater contamination is highlighted by the costs of cleanup efforts. Water utilities in the midwestern United States, a region that is highly dependent on groundwater, spend $400 million each year to treat water for just one chemical, the pesticide atrazine. According to the U.S. National Research Council, initial cleanup of contaminated groundwater at some 300,000 sites in the United States could cost up to $1 trillion over the next 30 years.
"Patchwork, end-of-pipe solutions are simply not enough," said Sampat. "To preserve this valuable resource, we need to make systematic changes in the way we grow our food, manufacture goods, and dispose of waste."
The report proposes retooling industrial agriculture to reduce farm runoff, a leading source of groundwater pollution. The EPA estimates that cutting agricultural pollution could eliminate the need for at least $15 billion worth of additional advanced water treatment facilities. Farmers from Indonesia to Kenya are learning how to use less chemicals while boosting yields. Since 1998, all the farmers in China's Yunnan Province have eliminated their use of fungicides, while doubling rice yields, by planting more diverse varieties of the grain. Water utilities in Germany now pay farmers to switch to organic operations because it costs less than removing farm chemicals from water supplies.
Companies also need to take greater responsibility for their toxic discharges. Sixty percent of the most hazardous liquid waste in the United States-34 billion liters per year of solvents, heavy metals, and radioactive materials-is injected directly into deep groundwater via thousands of "injection wells." Although the EPA requires that these effluents be injected below the deepest source of drinking water, some have entered underground water supplies in Florida, Texas, Ohio, and Oklahoma.
Manufacturers can reduce groundwater pollution by reusing materials and chemicals-thus reducing leakages from landfills. Companies are building "industrial symbiosis" parks in which the unusable wastes from one firm become the input for another. Such waste exchanges help an industrial park in Kalundborg, Denmark, to keep more than 1.3 million tons of effluent out of landfills and septic systems each year.
Manufacturers can also switch to less toxic alternatives. In Sweden, where chlorinated solvents are being entirely phased out by the end of 2000, some firms already report economic savings from switching to water-based solvents derived from biochemical sources such as citrus fruits, corn, soybeans, and lactic acid.
Sampat calls on governments to encourage reductions or replacement of toxic chemicals. One tool is fiscal policy. Pollution taxes in the Netherlands, for example, have helped the country slash discharges of heavy metals such as mercury and arsenic into waterways by up to 99 percent between 1976 and the mid-1990s.