Meeting Ecological And Societal Needs For Freshwater

ESA’s position paper notes that “society has been taught to think about the environment as something somewhere else. Ecological processes are not viewed as essential to our daily lives or strongly influenced by our actions. This perception needs to change if we are to protect and restore our vital freshwater ecosystems.” Changing the way freshwater ecosystems are viewed and used is a difficult but crucial task, says Jill Baron of the United States Geological Survey who chaired the Society’s paper. “A fundamental change in water management policies is needed, one that embraces a much broader view of the dynamic nature of freshwater resources and the short-and long-term benefits they provide.”

The paper states that it is in the long-term economic interest of society to work to protect and restore freshwater ecosystems. The benefits of healthy freshwater systems include food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life—all of which are costly, if not impossible, to replace with technological infrastructure. The sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations such as climate change, is critical to human well-being.

Natural freshwater ecosystems are dynamic, and therefore require a range of natural variation or disturbance to maintain their function. Human intervention, such as the building of dams, often narrows the range of variability, in turn causing changes in the ecosystem. For example, since the completion of the Glen Canyon Dam in 1963, measurable flows of the Colorado River to its mouth at the Gulf of California have occurred only six times, and the wetland area at the mouth of the river has decreased markedly as well. The lack of freshwater inflows has contributed to the endangerment of a large number of species in the Sea of Cortez, and the abundance of bivalve mollusk populations has dropped 94 percent from 1950 values. Water temperature can also change dramatically downstream of dams. Declines in the variability of monthly temperature along with reductions in species richness have been observed in the downstream waters of some dams in the western states. All these changes have ripple effects throughout ecosystems. For example, since they are filter feeders that remove many of the pollutants found in water, a decline in mollusks can lead to dirtier water, which can in turn threaten the well-being of other species.

Tools are available to restore aquatic ecosystems to a more natural and sustainable state, but are not being widely applied, according to the ESA paper. New statistical approaches to develop variable stream flows while still meeting hydroelectric and water supply needs have been applied or proposed for only several rivers, including the Flathead River in Montana, and the Colorado River. Variable streamflow techniques seek a compromise between water delivery needs for power generation or irrigation, and aquatic ecological needs for hydrological variability.

“The problems confronting freshwater ecosystems are intractable if they are approached piecemeal,” said ESA President Pamela Matson of Stanford University. “This position paper makes it clear that the needs of society and of freshwater ecosystems must be addressed collectively. Politically, this requires broad coalitions of water users working together toward a mutually acceptable future,” said Matson.

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Founded in 1915, the Ecological Society of America (ESA) is a scientific, non-profit, organization with over 7500 members. Through ESA reports, journals, membership research, and expert testimony to Congress, ESA seeks to promote the responsible application of ecological data and principles to the solution of environmental problems. For more information about the Society and its activities, access ESA's web site at: http://www.esa.org.