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<br />103 <br /> <br />season, evapotranspiration, from yeaetation llnd open wal~er 8urfacea lIlay" <br />utilize water at the maximWi' extent pos81bh, and at the expense o,f <br />baseflow. <br /> <br />Stre_ flow can be higher in spring ancl lower in fall in basins withe <br />substantial wetland areas than in basins with no lake "r wetland areas. <br />Ground water and surface water, and dischaqting and nondischarging wetlands <br />affect stream flow differently. transpiratIon water loss from wetland <br />plants often exceeds that due to evaporation, and is greater wi th tall than <br />with short emergent plants. Because both occur during the summer, the <br />combined loss of water through evaporation and transpiration was .76 m (2.5) <br />feet in some North Dakota potholes, far excc!eding the ,amount of annual <br />rainfall .304 m (1.0 feet) (Eisenlohr et al. 1972). ~hus, runoff ~s <br /> <br />essential for maintenance of the water level., and snowfall, esrly spring <br />rains, and carryover were essential for main.tenance of levels under dry <br />conditions. A slight modification of these water supplies shifts the <br />'prairie potholes to "wet" or "dry" cycles in a very short time (Weller <br />1981). <br /> <br />Indicators of Ground Water Supplies <br /> <br />We tlands may be good indicators of avaHable ground we ter supplies <br />(Carter et aI. 1978). Large numbers of wetlands in an area may indicate the <br />presence of an aquifer. Even a single >1l!tlllltld can be 'I good indication of a <br />large store of water and a potentially high liater supply in the more xeric <br />parts of the country. nood plain aquifers of many streams in the North <br />Carolina Piedmont could furnish large quantities of water to wells where the <br />perennial stream flow was adequate for recharging the ,aquifer (Carter et al. <br />1978). However, the reverse may be true for portions of Colorado and <br />Nebraska where wetlands show signs of drying due to excessive pumplng of the <br />Ogalala aquifer in excess of water replacement by stream flow from the <br />Platte River. <br /> <br />In summary, one of the strongest and most important biological <br />statements relating to wetland functions was made in 1977 by the U.S. <br />President upon issuing Executive Order 1 1990: <br /> <br />The ~~~tion's coastal and inland wetland.s are vital natural <br />resources of critical importance to thE! people of this <br />country. Wetlands are areas of great natural productivity, <br />hyd rological utili ty, and environmental. di versi ty, providing <br />natural flood control, improved water quality, recharge of <br />aquifers, flow stabilization of streams and riverll, and <br />habitat for fish and wildlife resources. Wetland!l contribute <br />to the production of agricultural products and timber, and <br />provide recreational, scientific, and ac!sthetic rE!SOurCes <br />of national interest. <br />