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3.1 Weather <br /> <br />In water use forecasting, it is typical to "weather normalize" base year water use. Water <br />use tends to increase with hot, dry weather and decrease with cool, wet weather. Hence, it <br />is important to adjust for abnormal weather pauems in order to establish an unbiased <br />starling point for the forecasts. <br /> <br />We collected monthly rain and daily maximum temperature data from the National <br />Atmospheric and Oceanic Administration for the Redwood City weather station over the <br />period 1945 to date. Our analysis of this data shows that weather during the calendar year <br />2000 was closer to normal than any other year in the series. This simplifies the weather <br />normalization task as thc 2000 water use data are already effectively weather normalized. <br />The annual weather values for 2000 and normal are shown in Exhibit 4. <br /> <br /> Exhibit 4. Weather for Year 2000 <br /> Description 2000 Normal <br /> Annual Rain (inches) 19.57 20.21 <br /> <br /> Annual Average of Dally Max <br /> Temperature (°F) 71.0 71.3 <br /> <br />3.2 Water Prices <br /> <br />Changes in water prices are also known to change customers' behavioral decisions <br />regarding water use. Following thc first law in economic demand theory, as thc real price <br />of a commodity increases, the quantity demanded by consumers decreases. <br /> <br />A review of RWC water prices shows thcy have remained relatively stable over recent <br />years after adjusting for inflation. This fmding of rate stability again simplifies the <br />analysis as there is no need to make water price adjustments to base year water use. <br />Appendix E contains the 2002 water price schedule. <br /> <br /> 3.3 Water (~onservation Technoloc, ies <br /> <br /> Water fixtures have tended to become more water efficient over time because of <br /> improvements in water conscrvalion technologies. In tiffs study, we specifically account <br /> for known water using efficiencies occurring with toilets and clothes washers. These are <br /> the two largest end uses of indoor residential water use, making up about half of total use. <br /> <br /> Toilet manufactures came out with 1.6 gallon per flush toilets, known as ultra-low flush <br /> toilets or ULFTs, in 1989. Toilets before this time used 3.5 gallon per flush or more. In <br /> January 1992, a California Plumbing Code change required all new toilets to be ULFTs. <br /> Many older, lass-efficient toilets were still being sold, however, at this time. A Federal <br /> plumbing code change effective January 1994 mandated ULFTs be used in all new <br /> <br /> Page 5 <br /> <br /> <br />