Doing a little research recently I learned that this trail is actually the west end of the Scorpion Mtn trail, if the trail log is to be believed.  The trail log, apparently from the 1950s, indicates that the Scorpion trail passes a junction with the Humbug Ridge Way trail and then heads down to Elk Lake Creek and Battle Creek shelter.  On the old maps the Humbug Ridge trail appears to be a continuation of the Scorpion trail but it is not.  The 1956 USGS quad shows both of these trails but not the trail down to Elk Lake Creek.  I have roughly drawn in the route of the trail down to the creek.

Here is the page from the trail logs describing the Scorpion Mtn trail.  The distance from the Humbug trail junction to Elk Lake Creek is consistent with the mileage recorded by my gps.

The reference in the log to the Welcome Lake Trail at 9.30 miles is something of a mystery.  I don't know what trail this might be.  There is that metal sign not far from the creek, but it points to Elk Lake not Welcome Lake.  Welcome Lakes are in the opposite direction. The original Elk Lake trail is on that side of the creek so perhaps that's what the sign is referring to.  I did not notice any other trails when I was there.  I've found that these trail logs have been reasonably accurate on other trails I've searched for, so it makes me wonder what this is all about.