I've never been, but based on the hints and lack of a portage sign where I assume there used to be a portage sign in the photo, is it the Gordon Lake to Rock creek "portage"?
Oddly enough the Gordon portage had signs at both ends. Depsite being a bushwack marked by trail tape. This is definitely the closest guess so far. BTW. After paddling Gordon Lake I strongly believe it should have at least one campsite. Not sure why it doesn't . It's a beautiful little lake.