|The Fall River Valley delimits the southwestern boundary of the watershed. At this lower end of the watershed, the Pit River slowly winds through the valley floor. Oregon ash, cottonwoods, and willow trees dominate the riparian overstory and provide cover and food for many migrant and resident birds as well as numerous mammal species. Many of the perennial agriculture crops also provide important habitat for wildlife species, especially geese, deer, and raptors. Several large remnant stands of Ponderosa pine are present in the valley.
The northern end of the valley is largely uncultivated and host to Ahjumawi Lava Springs State Park. One of the largest springs in the country emerges in the park.