Sylvan Lake is a city in Oakland County in the U.S. state of Michigan. A northern suburb of Detroit, Sylvan Lake is located roughly 26 miles fr…Sylvan Lake is a city in Oakland County in the U.S. state of Michigan. A northern suburb of Detroit, Sylvan Lake is located roughly 26 miles from downtown Detroit, and borders Pontiac to the east. As of the 2010 census, the city had a population of 1,720. With a land area of 0.51 square miles, Sylvan Lake is the fourth-smallest city by land area in the state after Clarkston, Petersburg, and neighboring Keego Harbor.