The most likely potential source loss for the City is a reduction of supply due to the JVWCD Drought Contingency Plan. At the different drought levels, JVWCD could implement reductions in supplied water by between 5 and 30 percent of typical use. Table 4-2 shows an example of the water surplus and deficit with a Level 2 (10%) drought reduction from JVWCD and Table 4-3 shows the same information with a Level 4 (30%) reduction. These tables do not include a supply redundancy buffer in the projected demands as this is already specifically represented through the reduction in supply availability. They also do not include future changes, such as moving large outdoor watering to secondary water, which will reduce the demand. These scenarios were chosen to illustrate the effect on the total City supply with a couple of the drought level scenarios if no changes were made. Similar tables could be prepared for other levels of drought but are excluded here for brevity.
For perspective and based on information from JVWCD, a Level 4 drought is extreme and is expected to occur very rarely, if ever. Conversely, Level 2 drought represents a significant but not unlikely level of drought, typical of what might be observed periodically as a result of normal variability in water supply. The most recent water year (2020-21) may have been around a Level 2 drought had JVWCD's Drought Contingency Plan been in place at the time.
Year | Reduced JVWCD Contract (Acre-Ft/Yr) | Well Production (Acre-Ft/Yr) | Projected Water Demand - High Estimate (Acre-Ft/Yr) | Surplus / (Deficit) (Acre-Ft/Yr) |
2021 | 18,150 | 2,500 | 25,600 | (4,950) |
2026 | 28,300 | (7,650) | ||
2031 | 31,000 | (10,350) | ||
2041 | 33,600 | (12,950) | ||
2051 | 34,900 | (14,250) | ||
2060 | 35,200 | (14,550) |
Year | Reduced JVWCD Contract (Acre-Ft/Yr) | Well Production (Acre-Ft/Yr) | Projected Water Demand - High Estimate (Acre-Ft/Yr) | Surplus / (Deficit) (Acre-Ft/Yr) |
2021 | 14,450 | 2,500 | 25,600 | (8,650) |
2026 | 28,300 | (11,350) | ||
2031 | 31,000 | (14,050) | ||
2041 | 33,600 | (16,650) | ||
2051 | 34,900 | (17,950) | ||
2060 | 35,200 | (18,250) |
As shown in the tables, expected supply during drought conditions is not expected to be adequate to meet normal City demands, even without the recommended supply planning buffer identified in the previous chapter. In order to stay within the available supply, the City will need to enact policies that will reduce its demands during periods of drought. Because the City uses JVWCD for the large majority of its water supply, the reduction in demand will need to nearly match the reduction in supply from Jordan Valley. For example, at Level 2, JVWCD will reduce their deliveries by 10% of the typical use. This results in a need for an approximate 9% reduction in total system demands. At Level 4, which is a 30% reduction from JVWCD, the City must reduce total system demands by approximately 27%.