Originally opened by the Portland City & Oregon Railway Company (1901–1902) as a freight interchange yard and power house site in 1902, it became a stop-gap storage location for interurban cars in 1906 after the Milwaukie carbarn was found too small for use, but before the Sellwood carbarns were constructed. The site grew into a sprawling terminal yard with carbarns, freight houses, etc. and lasted right until the end of the electric traction era.
The power house – a temporary facility constructed before the Cazadero plant came online – was supposedly located at “at the approach to the Madison-street bridge”, but locking down a precise location for it has been difficult.
A reference in an April 19, 1909 article to it being located directly above two water mains that crossed underneath the Willamette River to the West Side and about 300 feet east of the shoreline leads me to believe that it is the building marked as “vacant old car barn” on the 1909 Sanborn map of the terminal grounds. The size and orientation are consistent with earlier descriptions of the plant, which mention it being around 125 by 50 feet and oriented in an east-west direction [September 8, 1902 below], and the map also clearly shows the two water mains passing very close to it. Obviously, all the machinery had been removed at this point in time, as Sanborn maps normally show this in great detail.
The modern location of this building would be between SE Water and SE First avenues, just north of the centre line of SE Stephens Street. This would put it in the car park for the OMSI outbuildings on the east side of Water Avenue. Interestingly, a shed in that carpark is angled to exactly the same orientation as the car barn and repair shop that stood there in 1909 – surely they’re not the same building?