2025 Orange County Water Demand Projection Model
vary over time. The panel approach fits consumption data from all retail agencies simultaneously, improving model accuracy with a larger sample size. Hazen evaluated model fits using R 2 values as well as visual confirmation that the modeled historical water use captured long-term trends, drought restrictions, and COVID pandemic work from home orders. The models demonstrated strong performance in replicating historical consumption patterns over the past decade. Most regressions achieved R 2 values of 0.80 or higher, indicating a high degree of explanatory power. Model results show: Single-family consumption is highly seasonal, and the econometric model correlates well to seasonality and temperature. Multifamily use is generally less responsive to weather than single-family demands as some outdoor use has been shifted into the irrigation sector. Seasonal price elasticity varies the least between months for the multifamily sector. CII use per job is positively correlated to each job proportion as well as gross domestic product throughout Orange County. Irrigation is much more responsive to temperature and precipitation than the other sectors. Seasonal price elasticity varies the most between months for the irrigation sector. The Hazen team worked with each retail agency to calibrate sectoral model equations and quantify other uses (those not included in the single-family, multifamily, irrigation, or CII demand sectors).
Baseline Forecast
Forecasted demand is a function of both the change in driver units into the future as well as the change in explanatory variables. Table ES-3 summarizes the future drivers and variables.
Table ES-3: Future Model Parameters
Data Category
Variable
Source
Assumptions
Historical households per account; averages are multiplied by households projected by CDR Accounts are assumed to be constant into the future
Single-family and multifamily accounts
CDR
Driver Units
Agency Billing Data
Irrigation accounts
Proportion of jobs within CII sectors projected by CDR
Sectoral employment
CDR
Monthly Maximum Temperature and Total Precipitation
PRISM
30-year historical normal weather
Explanatory Variables
Prices increase by 3% per year above inflation for 2025-2030 and keeps pace with inflation thereafter (zero difference from inflation trend)
Water Price
Retail Agencies
8
Appendix G - 13
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