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9 WATER USE -' A portion of the lands being converted from agricultural to municipal use In the metropolitan area are dry farmed and It Is necessary when these lands are converted for additional water suppl ies to be developed. Under normal Irrigation practices the amount of water required at the farm headgate for Irrigation of one acre of farmland Is adequate to supply about one gross acre of urbanized land. Under average conditIons approximately 60% of the urbanized area will consist of lawns and parks, requiring irrigation. Water available for the other 40% of the land which is not irrigated can be used to supply the normal household and industrial requirements. On the average, agricultural land requires two and a half to three acre-feet per acre per year at the farm headgate for one acre of land. Of this amount approximately 40 to 50% Is consumptively used through evaporation from the soil surface and by plant transpiration. On the other hand, the method of irrigating lawns is much more efficient than farm irrigation, ranging up to 85 to 90% efficiency, Therefore, return flow from Irrigation of lawns is considerably less than return flow from irrigated farm land. The amount of return flow from Irrigated farming is substantial and ranges between 30 and 50% of the water app lied. During the non-Irrigation season most municipal water is used for household and Industrial purposes, Measurements throughout the winter months Indicate that that the consumptive use of, municipal water in these months ranges from about one-half to about two percent of the water diverted. These values will depend to a large extent upon the condition of the sanitary sewers. In the case of old Sewer systems the water loss from these systems becomes a part of the ground water supply whereas in other cases the system may show more than 100% return to the stream through the sewage plant because of Inflow Into the sanitary sewer line from surrounding areas where the water table Is higher than the ,sewer 1 ine, .' With the encroachment of urban areas into irrigated agriculture areas the irrigation water used on these lands is converted to municipal use. Some municipalities have acquired early priority direct flow water rights to supply their entire needs. Others, such as Denver, have a combination of early and late priority direct flow water rights which are inadequate to supply all of the cities needs. In these cases storage water is developed or acquired to firm up the supply during periods of heavy demand when stream flaw is Inadequate to supply direct flow rights. An extremely low run off year may be used to determine the yield and adequacy of direct flow water rights for supplying municipal needs. When carryover storage water and water from direct flow rights are used conjunctively, however, an extremely dry year may not be critical with regard to provision of a firm water supply. In these cases it Is necessary to select a series of law run-off years to make studies of the yield of the direct flow and storage rights throughout the entire period to determine whether the rights are adequate to meet the city's requirements. .- Under the Federal Decree, in Consolidated Cases Numbers 5016 and 5017, differences between Western Slope Inteeests, the Northern Colorado Water Conservancy District and the cities of Colorado Springs, Englewood and Denver were resolved. One of the provisions in this degree was that return flow from transmountaln diversions by the cities of Colorado Springs and Denver was to be re-used, provided such use can be done economically and Is legally feasible. The State Engineer has ruled that "...the city of Colorado Springs Is permitted to ~tilize the waters diverted from the Blue