3.3 Population
IRWD serves all or portions of seven cities, plus part of unincorporated Orange County. IRWD’s service area, once largely an agricultural community, has been converting to municipal and industrial development with more vacant land and farmland urbanized each year. IRWD's service area population is currently estimated at 450,323 as of January 2025, and IRWD’s estimated daytime population (the number of people present in an area during normal business hours, including commuting workers) is approximately 600,000 persons. The current and projected population data shown in DWR Table 3-1 below was developed based on information from the Center for Demographic Research at California State University, Fullerton (CDR) in 2026. The CDR approach has been approved by DWR. CDR developed projections for non-census years using California State Department of Finance Data combined with Geographic Information System (GIS) information. Annexations and boundary changes for water providers have been incorporated into these annual estimates. Table 3 - 1. DWR Submittal Table Retail Population: Current and Projected
DWR Submittal Table 3-1 Retail: Population - Current and Projected
2025
2030
2035
2040
2045
2050 (opt)
Population Served
450,323 478,599 NOTES: Population values as calculated by the Center of Demographic Research at California State Fullerton. 464,444 466,475 468,404 471,202
3.4 Local Climate
IRWD’s service area has a generally mild and relatively uniform climate with an average annual rainfall of 13 inches. In the past five years, annual precipitation in the local area has ranged from approximately 7 to 23 inches as recorded by the local California Irrigation Management Information System (CIMIS) station referred to as Santa Ana #75. Historic climate characteristics for evapotranspiration (ETo), precipitation, and temperature are shown below in Table 3-2 , Table 3-3 , and Table 3-4 .
3 - 5
IRWD – 2025 Urban Water Management Plan
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