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Reclamation announces Yakima basin May water supply forecast

Media Contact: Marc Ayalin 208-378-6203
For Release: May 3, 2024

YAKIMA, Wash. – The Bureau of Reclamation’s May 2024 total water supply available forecast for the Yakima basin indicates the water supply will not fully meet irrigation demands this season. The early estimate of the Total Water Supply Available for the May-September period indicates Senior water rights will receive 100% full entitlements, but junior water rights will receive 54% of their full entitlements.

Storage in the Yakima Basin Reservoirs on May 1 was 54% full with 580 thousand acre-feet, which is 72% of average. Precipitation for April was 57% of average and for October-April was 82% of average.  On May 1, the amount of water in the snowpack, known as snow water equivalent, was 65% 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.

Reclamation will provide an updated water supply forecast monthly—at least through July—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 May forecast is based on flows, precipitation, snowpack, and reservoir storage as of May 1, along with estimates of future precipitation and river flows. Other future weather conditions that determine the timing of the runoff and the demand for water also are critical in determining stream flows, the extent to which the reservoirs fill, and the water supply for irrigation.

For more information, visit Reclamation’s website at

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