2.1 Basin descriptions

We focused on the Willamette river basin (WRB) and the Yakima river basin (YRB), which are both part of the Columbia River watershed, located in the Pacific Northwest United States (Figure 1). The WRB in central Oregon covers an area of 29,636 km² with 9756 individual stream reaches, while the YRB in southeastern Washington state is approximately half the size (15,887 km²) and contains 6538 individual stream reaches (Figure 1). We selected these two basins because they differ in terms of biophysical characteristics (Fulton et al. 2024), including precipitation, topography, and land cover (Figure S1).