Back in the days before color film was the norm, photographers would hand color photographs. The coloring agent was chalk like, and is still available today. That's most likely not a signature, but an order reference name and number. It's a nice photo, and a lot of work went into colorizing it, but very limited value, unfortunately.
Back in the day...I drove in from Calgary on my way to Jasper NP to play golf. I was captivated by the beauty of that lake and the surrounding mountains; far more impressive than my golf rounds. Then drove out of Jasper NP to Edmonton stopping (for some unknown reason) at a little town named MacKay.
Don..........
I was there in the mid-70's. The lake get's it's color from the silt from the glacier at the head of the lake.It ranges from emerald green to a really bright turquoise blue....Really beautiful place to visit.