Washington state is characterized by a diverse hydrology that is heavily influenced by its climate and geological features. The state's major surface flows are the Columbia River, Snake River, Yakima River, and Spokane River. These rivers are fed by numerous tributaries and are regulated by large reservoirs such as the Grand Coulee Dam and the Bonneville Dam. The state's mountainous terrain and heavy snowfall create significant watershed systems that contribute to river flow, with the snowpack in the Cascade Range being a primary contributor. Climate patterns such as El Niño and La Niña can impact precipitation rates and snowpack levels, leading to drought or flooding events. Overall, the hydrology of Washington is a complex and dynamic system that is heavily influenced by both natural and human factors.