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-8- I I I I I I I 1 I I I I I I I t I I t A water use factor approach based on gallons consumed per household per day was selected. This approach can be easily related to gallons per tap or gallons per capita forecasting methods and allows for limited sectoral analysis where appropriate. Several key assumptions and methodological determinations were made to support the forecasting approach. Population and household projections were exhaustively analyzed, and persons per household ratios were carefully developed. Gallons per household per day (GHD) assumptions were thoroughly researched and incorporated each individual water provider's views about existing and future conservation programs. A number of service area definition and water accounting issues were also addressed on an individual supplier basis. Separate assumptions facilitated the projection of peak day water use, raw water demand, and end use water requirements. A peak day to average day ratio was developed for each supplier. Conveyance losses, and other adjustments from the source of supply to the treatment plant, and distribution system losses were also evaluated on an individual supplier basis. A meticulous review and modification process was followed to ensure that water supply entities in the study area were in agreement with, or at least understood the basis for, the demand projections. Each entity was encouraged to review draft forecasts, and modifications were made to a number of projections on the basis of individual discussions with those water suppliers. Demographic Forecast Scenarios Three series of population and household projections, identified as Scenarios A, Band C, were prepared for the Regional Water Supply Study. Scenarios A and B, respectively, represented high and low projections, and Scenario C was a mid-range projection. For the purposes of the Regional Water Supply Study, Scenario C was selected as the basis for planning.