Yakima Basin Water Supply Mid-May Release

Media Contact: John Redding, (208) 378-5021
David Murrillo, (509) 575-5848 ext. 213

For Release: May 19, 2005

The Bureau of Reclamation has released a Mid-May 2005 forecast for irrigation water supply in the Yakima Basin, according to David Murillo, Yakima, Washington project manager. The Mid-May 2005 forecast shows an increase in the total water supply available. The wet and mild conditions this spring in the Yakima Basin have helped improve the water supply. Even though the outlook is improved, it continues to indicate severe prorationing for junior users.

The Yakima Field Office declared official prorationing on April 6. Rationing is in effect at this time.

Senior water rights holders will receive their full water supply. The adopted prorationing level for junior users updated Mid-May is listed below:

Adopted prorationing level: 38 percent of full supply.

Precipitation for the period March 1 to May 17 is 114 percent of average. Runoff during May has been greater than anticipated. Irrigation demands have been moderated by the cool, rainy weather and the Yakima Basin reservoir system continues to fill.

Future precipitation is only one factor affecting the water supply. The weather conditions that determine the timing of the run-off and demand for water are critical in determining the extent to which the reservoirs fill, the amount of water available for irrigation, and rationing levels. Because of these unknown future factors and uncertainty in the basin conditions, the Yakima Field Office provides a likely range for the total water supply available estimate and the associated rationing level. In Mid-May, a reasonable range for the rationing level is between 32 percent and 49 percent of full supply with the adopted rationing level at 38 percent of full supply. The total water supply available will be adjusted bi-weekly or as needed to reflect changing conditions. The next update will be released June 6.

The water supply can be improved through prudent use of water. Please conserve water!

Untitled Document

Reservoir storage on May 18


Content (acre-ft)

Total Capacity

Percent of Capacity




66 percent




69 percent

Cle Elum



82 percent




100 percent




99 percent




81 percent


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