YAKIMA, Wash. – The Bureau of Reclamation’s May 2023 water supply forecast for the Yakima basin indicates the water supply will be adequate to meet irrigation demands this season. The May–September total water supply available would provide senior water rights 100% of entitlements and junior water rights 86% of entitlements, an increase from last month.
Storage in Yakima basin reservoirs on May 1 was a little more than half full at 610,000 acre-feet, which is 76% of average. Precipitation was 112% of average in April and was 75% of average for October–April. On May 1, the amount of water in the snowpack, known as snow water equivalent, was 99% of average.
Reclamation manages water in the five Yakima Project storage reservoirs, which is used along with other unregulated flows in the basin 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. Senior rights will not be reduced this year.
The May forecast is based on flows, precipitation, snowpack, and reservoir storage through May 1, along with estimates of future precipitation, river flows, and irrigation return flows. Other future weather conditions that determine the timing of the runoff and demand for water are also critical in determining stream flows, extent to which the reservoirs fill, and water supply for irrigation.
Reclamation will provide updated water supply forecasts monthly through July using the latest data each month to reflect changing conditions.
For more information, visit https://www.usbr.gov/pn/hydromet/yakima/.
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