Long Valley is an approximately long endorheic basin in the northern portion of Washoe County, Nevada in the northwest corner of Nevada. It is bordered by the Hays Canyon Range to the west, which gradually transitions into rolling hills north of the valley. To the east lies a large plateau, which is partially dissected by Massacre Lake Valley; this plateau eventually rises to over 7,000 feet in elevation as it rises toward the Sheldon National Wildlife Refuge.