2025 Orange County Water Demand Projection Model
2 2.2 2.4 2.6 2.8 3 Jan-10 Sep-23 May-37
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Historical
Projected
Historical
Projected
Figure ES-2: Demographic Parameters
While increasing density, decreasing persons per household, and increasing prices are expected to moderate demand, they do not fully offset growth in multifamily driver units. Table ES-4 shows the slow growth trend out to 2050 for all of Orange County.
Table ES-4: Orange County Forecast
Forecast Year
2025
2030
2035
2040
2045
2050
Single-family Demand (AFY)
196,682
189,600
189,594
190,010
189,146
188,368
Multifamily Demand (AFY)
91,462
93,631
95,823
97,339
97,976
98,583
Irrigation Demand (AFY)
88,837
86,849
86,849
86,966
86,849
86,849
CII Demand (AFY)
82,873
87,224
89,565
91,928
93,866
95,492
Other Demands (AFY)
28,194
28,007
28,314
28,613
28,735
28,831
Total Demand (AFY)
488,049
485,312
490,145
494,856
496,572
498,124
Single-family demand remains relatively flat due to limited growth in single-family housing units, and multifamily demands are forecasted to increase steadily, driven by rising multifamily housing development. Irrigation demand is expected to remain flat, and other uses (e.g., fire flows, construction) are projected as a fixed percentage of total use. Under expected future conditions, total Orange County demand is projected to remain relatively stable through 2050.
Alternative Forecasts and UWMP Scenarios
As part of this model, alternative demand forecasts were developed to evaluate the impacts of climate change and long-term water rate increases on future water use in Orange County. Using CMIP6 climate models and downscaled LOCA2 data from CalAdapt, the model applied temperature and precipitation deltas to historical weather patterns across four Flume-defined microclimate quadrants. These projections
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Appendix G - 15
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