More than 700 farmers and groups, including the Klamath Tribes, all claimed that their water rights were older than the state’s records, which only go back to 1909.

In 1975, the state began the process of sorting through and verifying the claims- called an adjudication. Similar water disputes have taken place on the Snake river in Idaho and in the Yakima basin in Washington.

In the Klamath, groups spent 38 years contesting who holds the senior water rights on tributaries like the Sycan River.

Ganong says the state considered evidence ranging from old maps to records in pioneer diaries to notes in bibles - and a treaty the tribes signed in 1864.

The Oregon Water Resources Department wrapped up the first phase of the adjudication this year. The date of the tribe’s right? Time immemorial.