Neither Northern Pacific or Milwaukee Road had the quantity of snow sheds that Great Northern or Southern Pacific built.
The Milwaukee Road had several wooden snowsheds on Snoqualmie Pass in Western Washington; one on the East side along Lake Keechelus ( Stump Lake to the locals ),and one ( or maybe two ??? ) on the West side. Part of one West side shed is still standing; you can bike or hike through it on the John Wayne Iron Horse Trail. MILW also built wood snowshed extensions to the Summit Tunnel on St. Paul Pass, on the Montana / Idaho border. East Portal was the station on the Montana side, while Roland was on the Idaho side.
The Northern Pacific did not have snow sheds as such, only wood extensions to the Stampede Tunnel. The East tunnel portal extension at Martin, WA. was well photographed as a waterfall ran down the hill side behind & ran under the snow shed, not over it as some have claimed. This wood shed was torched by vandals while the line was embargoed in the early 1990's; when BNSF re-opened the line this shed was replaced by a concrete shed.
Northern Pacific also built snow shed extensions on both portals of Tunnel 4, just West of Stampede Tunnel. The East Portal shed is gone, however the West portal shed has been replaced by a metal structure.