Big Horn Lake
Watershed Hydrology
The Big Horn Lake watershed, located in northwestern Wyoming and southeastern Montana, covers an area of approximately 2,247 square miles. The hydrology of the watershed is dominated by the Big Horn River, which is fed by snowpack in the winter and spring. Snowpack in the Big Horn Mountains typically peaks in early April, with an average snow water equivalent of 15 inches. Surface water in the watershed is mainly supplied by the Big Horn River and its tributaries, including Shell Creek and Greybull River. The reservoir formed by the Yellowtail Dam on the Big Horn River serves as a major source of water for irrigation and hydroelectric power generation. The watershed experiences a semi-arid climate with hot summers and cold winters. Over the past few decades, there has been a slight increase in both precipitation and temperature in the region.