Ecology v Acquavella

The historic Ecology v. James Acquavella, et al. adjudication, which determines and confirms all surface water rights in the Yakima River Basin, will soon be final. The Court intends to enter a Final Decree on May 9, 2019 at the Yakima County Courthouse. 

Also called the Yakima River Basin adjudication, the case prioritizes about 2,300 water rights in the Yakima Basin including Benton, Kittitas, and Yakima counties, and a small portion of Klickitat County.
Canyon view of Yakima River - Photo by Tom Tebb

After 40 years, Acquavella adjudication coming to a close

Read about it in our blog.

In the final stages

After 40 years of court proceedings and deliberation, Yakima Superior Court Judge F. James Gavin entered a proposed final decree and its associated draft schedule of rights for the Acquavella Adjudication on Aug. 10, 2017.

This opened a period for interested parties to file objections and set the stage for the court to enter its final judgment. Written objections were filed with the court on Nov. 15, 2017. Responses and replies followed until April 16, 2018. The court ruled on these objections on December 11, 2018.

The Court has now set a date for entry of the Final Decree on May 9, 2019. The Court will also enter an Amended Conditional Final Order for Subbasin 23 on the same date.  An updated final schedule of rights will be posted and referenced in the Final Decree.


In 1977, under the threat of drought, Ecology filed a petition for an adjudication to determine the legality of all claims for use of surface water in the Yakima River Basin. This began a process of meticulous research and testimony. The work substantiated nearly 2,300 water rights for individual properties in 31 tributary watersheds ("sub-basins"), and for 27 major claimants including irrigation districts, cities, federal projects, and the Yakama Indian Nation.

As each sub-basin's claims were determined, the court issued conditional final orders. The first conditional final order was filed in 1989. The conditional final orders for all sub-basins and major claimants will be referenced in the final decree. You can find links to the sub-basin orders and other important documents below.

Resources and important documents

Draft schedule of rights and updates
Court documents list, monthly notices and memoranda
Responses to objections
Replies to responses to objections