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<br />102 <br /> <br />SOlie wetlands may alternate between func~t1oning as recharge and <br />discharge areas. That is, during high water periods, water may be <br />discharged into an outlet, whereas during 101< water per:lods water may move <br />into the ground water and underground aquifers. <br /> <br />Water Quality Modification <br /> <br />A, combination of wetland factors operatl! to modify water quality <br />including in flowing water quality, soil, vegE.tation, and the extent of <br />evaporation, evapotransporation, discharge or recharge. Certainly, <br />out flowing water quality in natural, unalterEld wetlands reflects thE' quality <br />of the inflowing water and the interaction of the physical, chemical and <br />biological environment. The placid lIature of wetland Wllters caused by <br />little or no gradient and the density of vegetation serves to decrease <br />inflowing water velocity which thereby increases sediment deposition. Wate r <br />quality is affected through sediment deposition, storago! of organic <br />materials, absorption of metals and other ions and nutrient cycling., Water <br />moving out of the wetland (by dischal:ge, recharge, evapc)ration and <br />evapotranspiration) is of a different quality than that which enters. Where <br />the seepage into the ground water has been calculated, :It tended to be less <br />than 20 percent of the total volume of water per season" but may be a <br />significant contribution toO the watetshed and to water quallty. Because the <br />resident flora and fauna is affected by water quality, it serves as an <br />indicator of water chemistry and ecosystem health. <br /> <br />Nondischarging wetlands retain 'Iirtually all of tho! inflowing :lnorganic <br />sediment and tend to fill over'long periods ~f time. nLscharging ~!tlands <br />also collect sediment, but often at a reduced rate comp'lred to the <br />nondischarging type. Large storm events and floods oft,en serve as reset <br />mechanisms by washing out beaver daWl and scouring sediments from the <br />wetland. When streams overbank into adjacent floodplai:ns and riverine <br />wetlands, 10-20 percent of the suspended sediment load :ls deposited as <br />overbank deposits (Wolman and Leopold 1957). Approximately 80 percent of <br />the sediment entering a Wisconsin wetland at the headwaiters of a spring <br />creek was retained (Novitzki 1978). Likewise, it was found that the <br />sediment yields in streams in north-eentral Wisconsin may be 90 percent <br />lower in basins containing wetlands than in '..atershedsidthout wetlands. <br /> <br />Streall Flow ll.e~ulation ': <br /> <br />. - -~- .~ '~-~" . <br />Although 1ncOmPletel~ stud~ea, riverine wetlands may rapidly collect <br />-j; f' .,1\", ",~ ,.,' ._.,1 ~ , <br />water; ~ro!lcU,l'ec;t. ',pt,',Clpitet1on,' overland flCllt, ground water inflow and <br />overbatiY' flooding resulting in a s,igtlificantrise in th,. local water table. <br />The gralui't ~return of SOllie of this _tel' can help' to maintain stream base- <br />flow. The result of this sequence of events is to spresd the water over <br />large areas, decrease its velocity, and significantly delay some of its <br />return to the stream base flow. Much of the water can be lost by <br />evaporation and evapotranspiration. Under other conditions wetland may <br />actually reduce low flows (Carter et al. 1978, Novitzki 1978). Wetland <br />soils ..y store aignificant quantities of watsr, but during the growing <br />