Background:  

The Dominion Forestry Branch (DFB) was created in 1899 to administer the forests of the Railway Belt lands of BC, a corridor 20 miles on each side of the CPR between Port Moody and the Alberta border (as well as forest lands in the future provinces of AB, SK and MB).  Within these lands DFB was responsible for forest conservation and fire protection, and it created a number of forest reserves between Ashcroft and Sicamous.  By 1915 DFB began erecting a series of fire lookout stations in each of the forest reserves as well as high risk forest lands outside the reserves; ultimately 12 lookouts were built between Ashcroft and Revelstoke with an additional lookout near Chilliwack.

Porcupine Ridge Lookout:  

DFB began construction of the Porcupine Hills lookout station in 1921, to detect fires within the Tranquille forest reserve.  The lookout was partly completed that season and finished in summer of 1922.  Also constructed in 1921 as part of this project was a telephone line from Kamloops to Pass Lake ranger station, thence by forest reserve trails to Criss Creek ranger station via Tranquille Lake and Little Cariboo plateau.  A spur line connected a patrol cabin at the east end of Tranquille Lake with the new lookout station on Porcupine ridge.  Total length of this line was over 37 miles.

The value of having a live telephone line present during construction projects in remote areas was demonstrated in the summer of 1922, when W F Myers, a member of the fire and improvement crew working on the lookout, was stricken by acute appendicitis on July 26.  The presence of the telephone line saved his life as an automobile was dispatched to the end of the road at Pass Lake to meet Myers, who was being carried out by packhorses, and sped him to hospital in Kamloops for surgery.  

 DFB operated Porcupine Ridge lookout from 1923 to 1930, when the Railway Belt was returned to the province.  Unfortunately the names of the Dominion lookout men who manned the station have been lost.   BC Forest Service (called BC Forest Branch at the time) operated the lookout in 1931, calling it either Tranquille or Cariboo lookout. E Skene was lookout man that year, earning $4.00 a day.  In a survey of the Tranquille Forest conducted by Forest Branch staff that same year, Mr. G. S. Andrews reported "the Cariboo Lookout on Porcupine Ridge is well-situated for a view to all points of the compass, except the north and north-east sectors.  It is a well-built structure served by the telephone line of the Forest.  It is also equipped with the usual accessories.  This improvement should be maintained." 

But due to the severe impacts of the Great Depression, the lookout was closed that fall and never re-opened.  The cabin slowly deteriorated, as noted by Richard Youds in his 1993 book The Bonaparte Plateau, and the pack trail from Tranquille Lake became overgrown and difficult to follow, until Kamloops Snowmobile Association became caretaker of the lookout and made substantial renovations to the structure.