North and South Twin Lakes are located in Vilas County, in the Town of Conover and the Town of Phelps. North Twin Lake is 2,788 acres with a maximum depth of 60 feet. South Twin Lake is 642 acres with a maximum depth of 43 feet. They are both drainage lakes with an inlet (Military Creek) and outlet (Twin River). The outlet is controlled by a dam, owned and operated by Wisconsin Valley Improvement Corp., headquartered in Wausau, WI. Both lakes are considered to be in the mesotrophic state on the trophic state index. A Trophic State Index is used to group lakes based on water chemistry data and explain the relative age of a lake. Lakes can be classified as oligotrophic – nutrient poor, young; eutrophic – nutrient rich, old; or mesotrophic, which lies between the two. Trophic state is a term that describes the condition of a lake, but is not an exact measure. Mesotrophic, North and South Twins category, has increased nutrients and more plants. North Twin Lake has two public boat landings and South Twin has one.

Early history of the area indicates French trappers arrived among the Ottawa Indians as early as the 1600s. The earliest surveyors were noted in this area in 1840. The Wausau-Ontonagon Trail and the Military Road were used for accessing the area. The Wausau-Ontonagon Trail crossed at the channel between North and South Twin Lakes and then met the Military Road on the east shore of North Twin. From there they both went north toward Land O’Lakes where Military Rd. continued on its journey to the Keweenaw Peninsula in Northern Michigan and the Ontonagon trail went to Ontonagon on the shore of Lake Superior.

Historically, the Twin Lakes area was noted for its great hunting and fishing, making it an attraction for outdoorsmen. As early at the 1880s, many resorts sprung up on the shores of North and South Twin Lakes, also known as Big and Little Twin. One of the original resorts on South Twin Lake is now run as Camp Birch Knoll, a girl’s camp, but most are now private residences.