It was suggested on one of the much earlier posts that the lake could be Little Molas Lake. I believe this is a much smaller body of water and may be adjacent to another smaller body of water. I don't have the map you do but does this support what you see on the map?
I spent a great deal of time driving Molas Divide in the 1970's when I lived in Durango and the resemblence of the Drumhead view and this area is very apparent.