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Information on OWASA's Long-Range Water Supply Plan 11 <br /> January 29,2021 <br /> Page 5 <br /> Figure 3:The Yield of OWASA's Water Supplies and Long-Term Water Demands <br /> OWASA has Sufficient Raw Water Under Most Conditions for Next 50 Years <br /> 16 <br /> 14 <br /> -u 12 <br /> °q Yield <br /> UP <br /> Q ++ <br /> t • � <br /> 6 Actual �� � �� Baseline, end 99th <br /> � <br /> � Demands Percentile Projections <br /> 3 <br /> n <br /> QC a <br /> 2 <br /> o <br /> 19M 1990 2000 2010 2020 20M 2040 2050 2060 2crm <br /> Fiscal Year <br /> 3. Model Future Risks <br /> How did OWASA develop its water demand projections? <br /> OWASA based its water demand projections on regional growth projections that were finalized <br /> in 2018 for the regional Metropolitan Transportation Plan, in which the Towns of Carrboro and <br /> Chapel Hill and Orange County participated. The transportation planning effort also included <br /> information obtained from UNC about its expected growth. This regional transportation planning <br /> effort used a model to estimate the number of new single family and multi-family dwelling units <br /> and non-residential square footage for 2045 and build-out conditions based on land use plans <br /> provided by the local governments. OWASA then applied water use factors estimated from <br /> billing data for each residential dwelling unit and each square foot of non-residential space. We <br /> assumed that build-out will occur in 2070. We tested this assumption, and it appeared reasonable <br /> assuming a linear rate of growth. More details on the methods used to develop the water <br /> demands can be found in this report. <br /> OWASA recognizes that estimating water demands in 50 years has much uncertainty. Growth <br /> could occur faster or slower than anticipated, different types of growth could occur than <br /> anticipated(new large water user could move to area), our service area boundary could change, <br /> and water demands could change depending on behaviors and technology. Climate change could <br /> also impact the rate of growth(will people relocate from coastal areas to the Triangle) and water <br /> use (will we use more water as temperatures rise). Thus we included an uncertainty analysis in <br /> our demand projections as illustrated by the grey shading in Figure 3 (more information is here). <br />