Reclamation announces Yakima basin September water supply forecast

YAKIMA, Wash. - The Bureau of Reclamation's September 2024 forecast of total water supply available for the Yakima basin indicates the water supply will not fully meet irrigation demands this season. The total water supply available for the May 21-September 30 period indicates senior water rights will receive 100% of full entitlements, but junior water rights will receive 52% of their full entitlements.

Storage in the Yakima basin reservoirs on September 1 was 272 thousand acre-feet, 26% full, and 56% of average. Precipitation for August was 194% of average and for October-August was 85% 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 provides updated water supply forecasts monthly-typically 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 reservoirs storage.

For more information, visit Reclamation's website at https://www.usbr.gov/pn/hydromet/yakima/.