The Yamhill Watershed covers an area of 1,958 square kilometers in northwestern Oregon. It is primarily located within the Willamette River Basin and is characterized by hills, forests, and agricultural lands which are watered by its creeks and rivers. The watershed is important for the hydrology of the region, as it is a significant source of surface water for communities and farms. The snowpack in the Yamhill Watershed is an important component of the hydrologic regime, with snowmelt contributing to peak flows in the spring. The watershed has several reservoirs, which provide irrigation water and recreation opportunities. The constituents of these reservoirs are largely tied to land use in the watershed, with agricultural and urban runoff impacting water quality. Climatic trends in the Yamhill Watershed include increasing temperatures and changing precipitation patterns, which are likely to impact the timing and availability of water resources in the future.