Water use in the western U.S. is managed by a system called the prior appropriation doctrine, which gives priority to those who claimed water rights first. This means senior water rights holders are guaranteed water before newer, or junior, users. As climate change brings more frequent and severe droughts, we expect these conditions to affect senior and junior users differently.

Our study looked at how this plays out in the Yakima River Basin, a key farming area in the Pacific Northwest. We mapped out farmland based on whether the owners had senior or junior water rights, and then analyzed their crop changes, crop yields, irrigation methods, and economic outcomes using both ground data and satellite imagery. If there were no clear differences in these areas, we looked at groundwater use to see if junior water rights holders were paying extra to keep their farms running during dry periods.

We also tested a machine learning tool, Prithvi v2.0, to see if it could help detect farm-level changes caused by climate stress, such as drought. This could be useful in better understanding how farms adapt and how policy might need to respond in the future.