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WETLAND FLOODPLAINS HELP MAINTAIN WATER QUALITY . ,Stu.dies oj heavi?)! polluted waters flowing through Tinicum .:Harsh in PennSJ'lvania have revealed sig- nifuant redurliom in biowgicai oX)'gen demand, phosphorous, and nitrogen wzthin three 10 five hours. . The value of Georgia's 2,300-acre Alco[y River Swamp Jor water pollution control has been esti- mated at $1 million a )'ear. The bottomland forested uJetlands along the river have been shown to filter impurities from flood waters. Riparian habitals suslilin t?CoJ)'Jttms IMI include numy large mammals smh IlS bear, lvhite-taikd deer, and caribou.. White-tailed deer, St. Andrews Ea)', Florida. - 10 especially in wetlands, can reduce erosion by binding the soil with its root sys- tems. rv1oreover, friction between the vegetation and the water dampens waves and reduces current velocity. Coastal barriers-elongated, offshore formations of sand and other unconsolidated sediments lying generally parallel to main. land coastlines-protect large portions of the coast, including estuaries, bays, and wetlands, from the direct effects of high water, waves, and currents caused by both normal and storm conditions. Floodplo.ins and wetlatufs not only help maintain 1.vala quAlity, the;' also provide a 'la/ural erJ['ironmen/ for diverse specres. Boltmnlo.nd harJu'ood swamp, Louisiana. Surface Water Quality Maintenance Natural floodplains can reduce the cost of waste \vater treatment and water quality maintenance; they can reduce sediment loads, process chemical and organic '\vastes, and reduce nutrients, thereby protecting the physical, bio- logical, and chemical integrity of water. Floodplains buffer rivers, streams. lakes, and estuaries from upland sources of pollution. Groundwater Supply and Quality Conditions beneath undisturbed floodplains can facilitate the infiltration and storage of water, permit groundwater recharge, purify \vater entering the aquifer, reduce flood peaks, and ameliorate the frequency and duration of low flows in groundwater systems. These functions help maintain and improve conditions for municipal and private wells, wildlife, irrigation, and watering livestock during drought. Living Resources Floodplains are among the most productive of the planet's ecosystems. Because of their relative abundance of \....ater, they provide habitat for a mul- titude of plant and animal species, and the energy and nutrients from their healthy function are passed along to organisms in adjacent and dmvn- stream areas. Wetlands \Vetlands are perhaps the most prominent and familiar of floodplain resources. They are lands transitional between terrestrial and aquatic systems and are covered by shallow water or have a water table at or near the surface. There are slightly in excess of 100 million acres of wetlands in the 48 con- tiguous states, and the majority of these are in floodplains. Florida, Loui- siana, and Alaska have the most v.'Ctland acreage. vVetlands are classified by the U.S. Fish and VVildlife Service according to five ecological systems, of which estuarine and palustrine \vetlands are best known. Estuarine systems include such coastal wetlands as salt and brackish tidal marshes, mangrove s\..'amps, and intertidal flats, as well as the deepwater habitats associated with bays, sounds, and coastal rivers. Palustrine \vetlands