GEF

Unit 1  |  Why Water Matters 28 Water, unlike oil, is essentially a renewable resource. However, a significant percentage of the water that people depend on for irrigation and other uses is actually nonrenewable on human time scales. This fossil water has accumulated over thousands of years in underground aquifers , and for the most part is not connected to surface water flows. Vital groundwa- ter reserves such as the Ogallala Aquifer in the west-central U.S. are rapidly being depleted by unsustainable use. An emerging and often overlooked piece of the global water crisis is the degradation of aquatic ecosystems . These essential natural areas include fresh and saltwater wetlands , estuaries, lakes, and rivers, and provide habitats to an enor- mous range of biological species. Aquatic ecosystems offer invaluable services to people, including fisheries, flood control, water purification, groundwater recharge, and recreation. Irrigation projects started in the 1960s destroyed the Aral Sea aquatic ecosystem. Steps are being taken now to try to restore it. Around the world, aquatic ecosystems are suffering from decreased water flow, pollution from agriculture and industry, invasive species , as well as and temperature, salinity, turbid- ity , and pH changes. There is a long list of aquatic ecosystems FOSSIL WATER Water that has remained in underground aquifers for long periods of time. AQUIFERS Underground layers of porous rock that allow the movement of water between layers of non-porous rock. AQUATIC ECOSYSTEMS Biological communities of plants, animals, bacteria, fungi, and other organisms in a body of water. WETLANDS A land area that is per- manently or seasonally saturated with water. INVASIVE SPECIES A biological species that is accidentally or intentionally brought from one area to another, causing damage to native ecosystems. TURBIDITY The level of suspended solids in a water body. PH A measure of the acidity or basicity of a liquid, like seawater. Lowered pH in the oceans has negative effects on marine organisms.