Margaret Lake is located in Kittitas County, Washington. The lake is a popular area for hiking. It's also stocked with rainbow trout.
Along with neighboring peaks and lakes, Margaret Lake was given its name by Albert Hale Sylvester, a topographer for the United States Geological Survey working throughout the North Cascades National Park Complex in the 1900s. The name is purported to be from the name of a sister of ranger Burne Canby who accompanied Sylvester on his camping trips.