There were two different Merrills at Eagle Lake, who were there in the same time frame, but not related. Merrill Campground, along with a flat, creek and a small mountain was named after Tehama County stockman, Samuel Merrill (1819-1882). In 1874, he incorporated the south end of Eagle Lake for summer grazing and eventually owning land there. His brother, Nathaniel sold the land in 1885 to S.A. Gyle for $1,281.
Then there was Captain Charles A. Merrill (1838-1901), who also arrived on the scene in 1874. It was his intention to tap Eagle Lake by means of a tunnel to irrigate the sagebrush lands of the Honey Lake Valley. He was so obsessed with the project, that he spent the remainder of his life on that venture. The Merrillville Road that takes one to the east shore of Eagle Lake is named for him.