Portage Lake is a natural lake, located in Onekama Township in Manistee County, Michigan, United States. The village of Onekama, Michigan is situated at the northeastern end of the lake. The Lake was first identified as Portage Lake in 1837, when Joseph Stronach named the natural stream at Portage Point that flowed into Lake Michigan as Portage Cr…Portage Lake is a natural lake, located in Onekama Township in Manistee County, Michigan, United States. The village of Onekama, Michigan is situated at the northeastern end of the lake. The Lake was first identified as Portage Lake in 1837, when Joseph Stronach named the natural stream at Portage Point that flowed into Lake Michigan as Portage Creek. In that same year, the U.S. Government survey identified the lake as "O-nek-a-ma-engk or Portage Lake". The 26th Congress first published this survey information. The first map to show and to name the lake was entitled "The State of Michigan and the Surrounding Country," published by John Farmer of Detroit in 1844.