Ecology v Acquavella

The historic Ecology v. James Acquavella, et al. adjudication, which determined 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 later in 2018, 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 can be filed with the court until Nov. 15, 2017. The court's schedule for responses and replies will follow as needed until April 16, 2018; see full details below.


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 subbasin's claims were determined, the court issued conditional final orders, and the conditionally confirmed water right holders were notified. The first conditional final order was filed in 1989. The conditional final orders for all sub-basins and major claimants are referenced in the proposed final decree.

If you have received notice about this adjudication

As the state's water rights manager, we mailed the proposed final decree and related court notices to all confirmed Yakima River Basin water right holders on Aug. 17, 2017. Note: if you received the notification but no longer own the property associated with this water right,  it is your duty to inform the court of changes of ownership. Please use this form to start this process.

Here are the important documents sent to all confirmed water right holders of record:

Draft schedule of rights and updates
Court documents list, notices and memoranda
Deadlines and how to file an objection and response

Resources, view-by-subbasin, and court documents

View a map of the Yakima River sub-basins, get the form to file a property change of ownership, order a copy of the draft schedule of rights, view the sample design of the adjudicated water certificates, and review the conditional final orders.
Responses to objections
Replies to responses to objections
Forms to divide, join, or substitute property owners