YAKIMA, Wash. – The Bureau of Reclamation’s 2024 Total Water Supply Available provided the senior, non-proratable irrigators 100% of their entitlements and the junior, proratable irrigators 52% of their entitlements for the May 21–September 30 period. A separate forecast is made for the water supply in October.
The forecast for the October water supply available for the Yakima basin indicates the senior water rights will receive 100% of their full entitlements, but junior water rights will receive 0.0% of their entitlements for the October 1–20 period, which means no additional water. Any users that have unused water remaining from the May 21–September 30 period may use that water in October.
Storage in the Yakima basin reservoirs on October 1 was 114 thousand acre-feet, 11% full, and 35% of average. Inflows to the Yakima Project reservoirs in September were 80% of average.
Reclamation manages the water in the five Yakima Project storage reservoirs, along with the basin’s unregulated inflows to fulfill water rights, water contracts and instream flow obligations. Water shortages in the basin are shared equally by the junior water rights, which represent over half of the water rights in the basin.
This Water Supply Available forecast is the last forecast for the 2024 irrigation season. The next forecast will be in March 2025. Reclamation provides updated water supply forecasts monthly—typically March through July of each year—using the latest data each month to reflect changing conditions as they develop. In a water-short year, Reclamation will add mid-month forecasts and forecasts after July as necessary to adjust for prevailing conditions.
The monthly forecast is based on flows, precipitation, snowpack, and reservoir storage through the 1st day of the month, along with estimates of future river flows. Future weather conditions also are critical in determining stream flows, irrigation demands, and reservoir storage.
For more information, visit Reclamation’s website at https://www.usbr.gov/pn/hydromet/yakima/.