Thanks, Earl. I knew you would most likely know the details about Cresco tank. Didn't the rotary train empty it on the way up at least once also? I remember a water stop there, (I have good recordings of the departure) that had section guys madly shoveling snow into the tanks around Hamiltons point.
The use of the term "regular service" is somewhat questionable. I normally use it to describe operations (typically freight hauling) either before steam was retired or a tourist passenger operation using steam started, like the C&TS.
There is enough variation in railroads out there that it doesn't fit every situation well. The C&TS took over from the Rio Grande in 1968-9 and clearly started operations to haul tourists. I.E. the Rio Grande operations were regular service until 1968. However, the Durango operation simply continued doing what they had always done. An argument could be made that even after the D&S came along, that "regular service" has simply continued on the Silverton branch. A clearer example would be the EBT. It was regular service until 1956. Tourist operation after that.