It’s getting hot on the Upper Klamath. This week, the Oregon Water Resources Department began telling ranchers to shut off irrigation; their rights to Klamath basin water are superseded by tribal rights.

Klamath tribes fought for decades to determine their rights to Klamath River water were the oldest, and won earlier this year. They were joined in calling for increased flows by the Bureau of Reclamation, which runs a federal irrigation project, and the U.S. Fish and Wildlife Service, as the AP’s Klamath guy Jeff Barnard has reported.

The tense political climate is not unfamiliar. Tribes were granted higher river flows in 2001, despite protest from irrigators in the upper basin. The next year, the roles reversed. The lowered flow in 2002, combined with a large run of salmon, led to the death of 33,000 fish. It was one of the biggest fish kills (or fish die-off, as the Bureau of Reclamation prefers to call it) the U.S. had ever seen.

This year is looking tough as well. It’s already shaping up to be a dry summer — the National Oceanic and Atmospheric Administration shows dry to drought conditions in Southern Oregon and Northern California already. Fishermen and biologists are predicting high numbers of salmon. And ranchers, now cut off from their usual supply, say there will be serious water shortages in the next few months.

Some people fear the shutoffs could spark violence. State watermasters — who are tasked with asking ranchers to turn off their water, or turning it off themselves — are traveling in pairs and notifying the sheriff’s office wherever they go, Barnard reports.

Meanwhile, more than 30 interest groups are still hopeful that Congress will pass legislation to remove dams on the Klamath. The joint agreement was voluntarily extended for two more years in December in the hopes that legislators will pass the proposed changes.