Groundwater problems spring to the surface.

Mankind's actions are noticeably harming groundwater resources worldwide, according to a recent report by the United Nations Environment Programme (UNEP). Across the globe, states Groundwater and Its Susceptibility to Degradation: A Global Assessment of the Problem and Options for Management, groundwater is being depleted by the demands of megacities and agriculture, while fertilizer runoff and chemical pollution threaten water quality and public health. By 2025, two-thirds of the world's population will live in a nation that is considered water-stressed.

The report is important because it demonstrates that groundwater issues, although often specific to a particular watershed, affect people worldwide, says Susan Seacrest, president and founder of the Groundwater Foundation. Besides those resources that are locked in glaciers and ice caps, groundwater accounts for about 95% of the earth's fresh water. According to the report, groundwater supplies drinking water for up to 2 billion people and 40% of the irrigation water used in agriculture; still more is used for industrial and other uses.

One major issue affecting groundwater is salinization, according to the report. Salinization often occurs as a result of poor irrigation (in which natural salts are forced through waterlogged soil into the aquifer) or the encroachment of seawater into aquifers (which can be exacerbated by overextraction of groundwater). Just a small amount of intrusion--around 6% salinity--renders water unfit for any purpose except cooling and flushing, the report notes, and remediation technologies are expensive and often beyond the reach of many developing countries.

In the introduction to the report, UNEP executive director Klaus Topfer calls for the establishment of a global surveillance network to monitor the extent and level of aquifer pollution: "Regional observatories of aquifer vulnerability and degradation could gain valuable knowledge through the comparison of water quality conditions, and the results would be a powerful public awareness tool."

But Bill Alley, chief of the Office of Groundwater for the U.S. Geological Survey, notes that even in a developed country such as the United States, monitoring can be difficult to sell to legislators and managers as a budgetary priority because it yields long-term, rather than immediate, benefits. The report itself says groundwater monitoring is often "inadequate and poorly focused," and that when environmental programs are scaled back, monitoring is often one of the first things to be cut.

Furthermore, once monitoring is in place in one location, it may not be adjusted as the ecologic dynamics within the watershed change. This ultimately results in less reliable data. Finally, water management is usually highly fragmented. For example, most municipalities have separate drinking water and wastewater departments, even though it all comes from and goes back to the same source. In the United States, both the U.S. Geological Survey and the Environmental Protection Agency have separate offices for groundwater and surface water management.

Options for rejuvenating groundwater resources include artificial recharge (such as replenishing groundwater with rainfall collected during wet periods) and desalinization, which Alley says is decreasing in cost although it is still expensive. However, the science and technology to support these approaches generally is available only in developed countries. Stephen Ragone, director of science and technology for the National Ground Water Association, notes that science should be shared with workers in less-developed countries so that they can gain more understanding of how to protect limited water resources.

It is important to study the quantity of groundwater and how it is used, not just the threats to the aquifer, Alley says. Groundwater and surface water needs to be looked at basin by basin in terms of how pollutants enter the system, and basic hydrogeologic principles to maintain water balance in natural systems need to be applied, according to Ragone. Alley and Seacrest say that groundwater should be included in water quality planning that is done in each watershed.

The final link in the chain of protection involves educating the public about the connection between unseen groundwater and the water that comes out of the kitchen tap, Seacrest says. This way, the public can make the connection between everyday activities and the potential that water pollution has to affect their daily lives. Contamination is hard to address once it occurs, she says: "Pollution prevention is the only viable strategy for groundwater."