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.

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. 

Final resolution of the case is expected in 2019, when adjudicated water right certificates will be issued.

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. 

Hundreds of water rights have been updated through multiple court orders since the proposed final decree came out.  Judge Gavin will now allow parties to file comments on these water right updates. Comments on these water right updates need to be filed with the court by Feb. 19, 2019 (see the order linked below for specifics). The court will then rule on any comments and then set a date for entry of 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