YBSA Monthly Report March 2020

Storage: The 5 reservoirs are at 63% full. As on April 1st, the water graph shows the reservoirs are slightly above average. The graph indicates that reservoirs fill rapidly from April through June providing the snowpack will be large enough to provide the water. The reservoirs hold 1 million acre/feet of water and the snowpack must provide an additional 2 million acre/feet to provide the needed water for instream flow (fish) and out of stream use (agriculture).

Projects in the Yakima Basin:
• Lake Kachess pumping plan is still being studied awaiting information on cost and available water.
• Lake Cle Elum fish passage continues with the Helix Project still moving forward.
• Continued improvement of habitat in rivers and streams for fish passage.

Lower Yakima River: Flows in the Yakima River are lower than needed for salmonoids to survive and move up stream. Low flows and summer hot temperatures are a deadly combination for the survival of salmonoids.

Columbia River Water for the Yakima Basin: The study evaluating the use of Columbia River water for the Yakima Basin was completed in 2008. It was labeled as the Yakima River Water Storage Feasibility Study. The following information was available for review by affected residents:

Availability of Columbia River Water – In the May 2002 Black Rock Reservoir Study Report, Washington Infrastructure Services (WIS) assumed Columbia River water was available for pumping whenever flows at Priest Rapids exceeded 130,000 cfs or spills occurred. On this basis, WIS concluded diversion could take place only in April, May, and June. Sizing of the Columbia River pumping plant and Black Rock Reservoir was based on these criteria plus various assumptions on water demand in the Yakima River basin.

Based on pending water right adjudication activities, the authorized maximum water deliveries for the two divisions for April through October is estimated as follow:

Solely for illustration purposes, assume Sunnyside and/or Roza are fully served from a Black Rock project and their Yakima River water is exchanged for other Yakima basin uses in the following sequence (1) for instream flow purposes in wet and average years, and (2) for
irrigation purposes to all other proratables (which total 790,000 acre-feet) to provide a maximum 70 percent supply in dry years.

A Roza and Sunnyside exchange would meet the 70 percent criterion plus make 240,000 acre-feet available for non-irrigation uses. In wet and average water years, and additional 810,000 acre-feet would be available for non-irrigation uses.