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APPENDIX B - DEMAND FORECASTING PROCEDURE <br />under current water conservation practices does not include an increase in the amount of <br />raw water being used for irrigation through 2017. <br />Residential and Multifamily <br />The City has separate billing categories for residential (single family homes and duplexes) <br />and multifamily (three or more attached living units) connections. There are two basic <br />approaches to forecasting residential and multifamily water use: forecast each category <br />separately, or forecast the combined residential and multifamily usage. For purposes of this <br />Plan the residential and multifamily categories were combined and forecasted as one <br />category. Using this methodology it is not required to determine the number of multifamily <br />dwelling units and the occupants per unit. If these billing categories were separated the per <br />capita water use for the multifamily units would be less since there is typically less <br />irrigation. Combining the residential and multifamily water use is a reliable forecasting <br />method. <br />The forecast is based on population projections and historical population and residential per <br />capita water use from 1997 to 2006. <br />The forecasting procedure for residential and multifamily is outlined below: <br />1. Confirm service area population projections through 2017. <br />TABLE <br />Population Projections (from 2004 Raw Water Master Plan Update) <br />Year Population <br />2007 <br />86,060 <br />2008 <br />86,723 <br />2009 <br />87,387 <br />2010 <br />88,050 <br />2011 <br />89,030 <br />2012 <br />90,202 <br />2013 <br />91,000 <br />2014 <br />91,980 <br />2015 <br />92,970 <br />2016 <br />937950 <br />2017 <br />947940 <br />2. Establish a per capita water use value that accounts for residential and multifamily <br />water use. <br />a. Correct residential water use for unmetered connections. For 1997 to 2006 sum the <br />metered residential and multifamily water use, including usage inside and outside City <br />limits. Multifamily units have always been metered, but residential single family units were <br />not fully metered until 2006. Water usage in the residential category was adjusted to account <br />for the percent of unmetered residential connections. <br />B -2 <br />