Diablo Reservoir is a man-made lake located near Newhalem, WA in the North Cascades. The reservoir was created in 1930 to generate hydroelectric power for the city of Seattle. The hydrology of the lake is heavily influenced by the Skagit River, which feeds into the lake. Specific surface flow comes from the Skagit River, as well as several smaller creeks and streams in the area. The reservoir is also a major provider of snowpack, which is critical for maintaining water levels during the dry summer months. The water from Diablo Reservoir is primarily used for hydroelectric power generation, but it also supports local agriculture and recreational activities such as fishing, boating, and camping. The surrounding wilderness is home to a variety of wildlife, including bears, mountain goats, and bald eagles.