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ordinance may find the impact of passive conservation to be more noticeable <br />in winter months. <br />The estimation of conservation savings requires an initial baseline forecast of <br />water demand without conservation. The baseline water demand forecast is <br />driven by projections of future demographic growth for the study area and <br />does not account for the effects of future water conservation. Impacts of <br />conservation savings can then be determined from the baseline water <br />demand forecast. <br />Table 14 provides a review of five studies of estimated conservation savings <br />that followed similar methodologies for estimating conservation savings. For <br />each study, the baseline forecast and estimated passive savings are shown. <br />In three of these studies, passive conservation was assumed to take effect in <br />new construction and remodeling prior to 1994 due to county or state <br />ordinances that were enacted prior to 1994. Each study assumed a <br />compliance rate of 90 percent for those end uses affected by plumbing codes. <br />Replacement rates for existing (pre-plumbing code) fixtures varied from 0.25 <br />to 1.0 percent per year among the studies. <br />The baseline demand in million gallons per day (MGD) of each study area as <br />shown in Table 14 provides an indication of the relative size of the water <br />demand study area. The forecast for the Alabama-Coosa-Tallapoosa - <br />Apalachicola-Chattahoochee-Flint (ACT-ACF) River Basins is a forecast for a <br />major U.S. watershed with a 1995 population of about 5.5 million people. The <br />forecast for the Orange Water and Sewer Authority (OWASA) is for a service <br />area of about 50,000 residents (1995) with water service to a major university. <br />Estimated passive savings as a percent of the baseline water demand is also <br />shown in Table 14 for each study. Passive savings as a percent of the <br />baseline forecast increase over time as new construction occurs and given the <br />replacement of pre-existing less water efficient fixtures. These estimated <br />savings continue to increase with the passage of time through the planning <br />horizon of each study. <br />Note that the percent savings in San Diego are more than the other study <br />areas in a given year. This is because California instituted state plumbing <br />standards in advance of the national plumbing standards. Thus, the percent <br />savings in San Diego are about one time interval ahead of the percent savings <br />in the other study areas. In addition, the passive savings tend to increase at a <br />greater rate over time for those study areas that expect to experience faster <br />growth rates since high growth rates result in a larger percentage of water <br />fixtures being water-efficient. <br />34 V. Conservation Impacts on SWSI Water Demand Forecast <br />