You are correct, Johnson's is bridge 32-A and as you say is just above milepost 31 as near as I can tell. The water tower was shown abandoned in the 1916 valuation report which was dated 9-26-16. The trestle was filled per AFE22 which makes me think it must have been filled shortly after the valuation report was done to have such a low AFE #. Here's some speculation about the water tower at this location. Trains traveling westbound in the early days would have watered at S wye water tank which is actually a ways below the actuall wye. They they would have often proceeded on past the wye to Sumpter to load/unload pass. baggage and mail. In the case of freights, they would have used up a bit of water between S wye and Sumpter as the grade steepens going into Sumpter as it does today and then they would have had a certain amount of switching to do at the warehouses and the lumber mill. Then they would have turned on the wye in Sumpter and headed back down grade to S wye (remember they won't pass the S wye tank as it is back down the main a ways) and then start up grade towards the summit. I am thinking that the small early motive power would have been ready for another drink by the time they got to the Johnson's tank, or at least have needed to top off in order to insure they could make it to McCoy, which is the next water stop.