BN/BNSF, UP and Milwaukee Road on Seattle's Harbor Island

I’m interested in Seattle’s Harbor Island as a possible location to model, and I’m hoping someone can provide information about the history of rail service on the island as well as insight into current operations. I’m considering both the present day and the early 70’s as potential modeling periods (you can weigh in on which period I should focus on in my other thread, "Which rainbow fleet would you model?).

The photo below, taken last summer, shows the yard on the west side of the island which is shared by BNSF and UP. BNSF uses the west half of the yard, while the UP restricts its operation to the east side. One function of the yard is to serve as a marshalling area for the weekly rail barge to Alaska, which is switched by the UP. Tax parcel maps show that the yard was once owned by the Milwaukee road.

Can you provide any information about operations on the Island today and around the time of the BN merger? Can you recommend a good reference work on rail operations in the Seattle area in the early 70’s? Any help would be appreciated.

Charlie