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Table 8 shows that with a supply from Lake Mead of 30.0 MG-D no storage will be retired to meet the total water requirements of the Urban area during the maximum day of 1970. However, the supply will not be adequate to meet the peak hourly consumption during this day. For the supply to meet hourly variations and hourly peaks during the max­imum day of 1970, mass diagrams of the estimated hourly consumption were prepared. From these data it is estimated that a total of 7.0 million gallons will be required to maintain a sufficient supply of water for local distribu­tion in the urban area during the maximum conditions in the year 1970. This storage is called “operating storage". Fire storage is often based on the requirements of the National Board of Fire Underwriters. According to these requirements fire flow is computed by the formula q - 1020 ,/P (1 - ,^P_ ) where "p" is the population in ( 100 ) thousands and is the fire flow in gpm. Storage should be adequate to sustain these flows for a period of ten hours. For si urban area population in 1970 of 75,000 persons, the NBFU reqiirements result in a fire flow of 8,060 gpm and fire storage in the smount of 6.6 MG-. These requirements appear well defined but in reality are rather indefinite inasmuch