White Pass Photo with Questions

One of our long time SVRR members visited the White Pass years back and road behind #73. He donated a great many photos from his collection to our SVRR Archive. This is one from his White Pass trip. Obviously they are topping off the tender using a pump in the creek. I presume this is near MP 14 based on the bridge number. The pump appears to be a submersible of some kind. What are the two small lines going to the pump? The first thing that comes to mind is a pump driving by a hydraulic motor, but then where would you get the hydraulics on the tender? I suppose you could have a small engine driven hydraulic pump. Was there a trackside water tank that no longer exists in this area?