Draft 2025 Urban Water Management Plan

2025 Orange County Water Demand Projection Model

were used to simulate two climate scenarios, dry/warm and wet/cool. The dry/warm scenario showed increased water demand due to higher temperatures, while the wet/cool scenario, when paired with a 3% annual price increase above inflation, demonstrated demand suppression. The 2025 Urban Water Management Plan (UWMP) requires agencies to project long-term water demand under three hydrologic conditions, normal year, single dry year, and five consecutive dry years, over a 20- year horizon in 5-year increments. In this model, the single dry year scenario used a hot-dry index (HDI) to identify the year with the most weather-sensitive demand, with 2014 selected for most agencies. The multiple dry year was developed to describe the potential impact of consecutive dry years. Figure ES-3 summarizes all forecasts.

700,000

650,000

600,000

550,000

500,000

450,000

Historical

Baseline Normal Year

Single Hot/Dry Year

2nd Hot/Dry Year

3rd Hot/Dry Year

4th Hot/Dry Year

5th Hot/Dry Year

High Demand Scenario

Low Demand Scenario

Figure ES-3: Baseline, Alternative, and UWMP Forecasts

Although Orange County demands are forecast to be relatively flat into the future, Figure ES-3 shows that annual variations in weather could cause high fluctuations.

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Appendix G - 16

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