The Snohomish watershed (HUC 17110011) covers an area of 1,915 square miles in western Washington State. The hydrology of the watershed is heavily influenced by the Cascade Mountain range to the east, which provides a significant portion of the snowpack that feeds the rivers and streams in the area. The Snohomish River is the largest river in the watershed and is fed by a network of smaller tributaries. The watershed is home to several reservoirs which serve as important sources of drinking water for the region. Surface water quality in the watershed is affected by human activities such as agriculture, forestry, and urban development. The climate in the region is characterized by mild, wet winters and dry summers. In recent years, the region has experienced record-breaking heatwaves and wildfires, indicating a trend towards warmer and drier conditions.