Water right adjudications

Adjudication is a Superior Court process that legally determines whether a water right is valid, how much water can be used, and its priority during shortages in a defined basin. It prioritizes each individual water right according to Washington water law's “first-in-time, first-in-right” prior appropriation framework.

Ecology’s Water Resources Program is responsible for managing the state’s water resources and has an important role in supporting the adjudication process and decisions.

Recent actions

In May 2019, the Yakima County Superior Court completed the adjudication process for the Yakima River Basin. This court ruling determined surface water rights for about 2,300 water rights. As of November 2019, with the completion of the Yakima Adjudication, there are 83 completed adjudications in Washington.

Areas under consideration for future adjudication

During the 2019 legislative session, the Legislature provided us funding to assess where the next water rights adjudication should take place. We are looking statewide to assess watersheds that might benefit from adjudication. We are considering basins with senior tribal water rights, streamflow needs, and challenges caused by water user uncertainty and conflict. We will follow a statutory process to compile information, consult with the courts, and submit a report to the Legislature that includes estimated budgets. This assessment is in its early stages. 

As of mid-November 2019, there are 66 requests for areas to be considered for adjudication. As part of our assessment, we will consider these requests as well as other relevant locations.

Benefits of adjudication

Determining the validity, extent, and priority of water rights within a sub-basin can be vital for:

  • Community planning.
  • Protecting the water resources of the state.
  • Protecting legal water users.
  • Supporting the transfer of water to new uses.
  • Preventing and resolving water conflicts.