The Bureau of Reclamation is out with its final Yakima Basin water supply forecast of the season. The October forecast indicates the senior water rights will receive 100% of their full entitlements, but junior water rights will receive 0% of their entitlements, which means no additional water. Any users that have unused water remaining from this irrigation season (May 21–September 30) may use that water in October.
Storage in the Yakima basin reservoirs on October 1st was 114 thousand acre-feet, 11% full, and 35% of average. Inflows to the Yakima Project reservoirs in September were 80% of average.
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.
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.
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 next water supply forecast will be released in March.
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