Unidentified spur near Durango

Perusing the Colorado/Utah map in Hilton's "American NG Railroads" recently I noticed something I'd missed. It shows spur or short branch leaving the main about 8-10 miles east of Durango (in the vicinity of Falfa which is not shown) and proceeding north for possibly 4-5 miles.......I'm estimating these distances, the map is drawn at about 40 miles/inch and is not terribly precise. Generally it shows only major branches without regard to temporary lines, mine spurs etc. With all the discussion here about the San Juan extension I don't recall hearing any mention of a branch line in this area. Assuming it must have been out of service at a fairly early date. I've been unable to find any mention of it in print or, in my limited library, a more detailed map of the area. Anyone know what this was, where it went, or what years it operated?
TIA,
J