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<br /> <br />summer and fall. Irrigation return flows have changed intermittent streams to perennial <br />streams with a year-round water supply; improved efficiencies may reverse this trend. <br /> <br />Another environmental resource impacted by irrigation efficiency changes is wetlands. <br />Losses from irrigation systems can augment the water supply for natural wetlands and often <br />result in creation of new wetlands entirely dependent on irrigation for their water supply. ' <br />Water that would otherwise return to the surface stream is consumed by wetland vegetation, <br />creating a stream depletion. Incidental consumptive use within an irrigation system is often <br />reduced with a corresponding loss of wetland acreage. Indeed, the Federal Salinity Control <br />Program has been required to mitigate this type of wetlands loss caused by its projects. <br /> <br />There are also socio-economic impacts associated with improv~d irrigation efficiencies. <br />The vegetation along ditches, which relies on conveyance losses for a water supply, has in <br />some areas become a major community amenity. Ditch lining eliminates this vegetation, <br />and replacing ditches with pipe eliminates both the vegetation and the artificial waterway. <br />In urban areas ditches serve as aesthetic and recreational surrogates for a natural <br />watercourse. On the other hand, transfer of increments of salvaged or saved water is <br />presented as an alternative to the total conversion of agricultural water rights to municipal <br />uses. Thus, rural communities may be spared the economic and environmental impacts <br />associated with large scale total dry-up of irrigated acres. <br /> <br />22 <br />