Eagle Lake's first real usage was by the Algonquin first nation of the area, who had a canoe route to access Lake Nipissing from the Georgian Bay. One of the pass-through lakes was Eagle Lake. Despite this, the first settlement wasn't by natives, but rather 2 European men - Henry Tough and William Smyth. These two settled the land surrounding Eagle Lake, for the purposes of logging. Sawmills were established on the south end of the lake, and logs can still be seen to this very day. After Henry's death, his son Bill continued the sawmill. But after 2 other failed attempts at sawmilling, the family sold the land to Charlette and Henry Smith. After they had resided there for a few years, they sold the land to the province in 1957. The day use opened the same year, with the campground opening in 1964.
Originally, this park was known as "Eagle Lake Provincial Park". But by 1960, there had been too much confusion with the many other Eagle Lakes in Ontario. And so, they changed the name to the word "Mikisew", which means "eagle" in Algonquin.
Info sourced from the image right.