I have a few S wye photo's from the old days on my computer. Maybe I'll try posting them tonight though if someone familiar with posting photos beats me to it so much the better as I've never done it before. As for the name, I don't have the dfinitive answer, but I doubt it is for Sumpter as there was a wye at the depot in Sumpter with one leg going on up country parrallel to Cracker Crk. which served some warehouses, and the other leg curved across the present main st. (not called main st.) by the motel and went back to the South along the hillside climbing a bit to the location of the Sumpter Lbr. Co. mill which is where people today refer to as the fairgrounds. You can see this grade in a few places.
I suspect the name S wye is more likely due to the curvature in the mainline going into Sumpter in the vacinity of where the actual wye was built. The wye was built after the mainline reached Sumpter in order to continue the mainline to points westward (by timetable).
In the old days, the water tank stood about a 1/4 mile above what we call "Bad Water Crossing" which is the service road to Sumpter's wastewater vacilities. The piers and foundation for the pump house are still there, but hard to spot unless you walk ROW. The tank was on the side of the track opposite to the highway and had a pump house on the far side of it from the track. The section crew had to regularly run the pump to fill the tower, but eventually the tower was connected to the City of Sumpter water system. Just below the water tank was a siding between the present main and the highwqy. Near the upper end of the siding next to the hwy. was a car house to keep the section crews motor car in. Between the water tank and the upper end of the siding was a storage spur on the same side of the main as the water tank. Above the upper sw. for the siding on the hwy. side of the main was a phone booth. A little ways above the upper siding sw. was the sw. for the wye. Also above the upper wye sw. going toward Sumpter was a fuel track that was a siding on the opposite side of the main as the present siding at South Sumpter, but in the same general vacinity. This area was dredged so no indication of the original allignment is present. Somewhere in the area around S wye there was an additional storage spur constructed under AFE 223 5-31-24, which was 968', but I have no mapping reference to where it was on the ground.
At S wye at some point at least one box car was put out on the ground as quarters for a section hand and his family. I have talked to a guy who said his family nearly froze to death living in that box car one winter. Coach 20 was also eventually put on the ground at S wye as a MOW shed or quarters.