@bitsandbass
It is navigable from Long Lake to Sebago through the Songo Locks and visa versa. I haven’t gone through them so you’ll need to research If there’s restrictions at certain times of year etc. I’ve heard it’s free flowing at times (during fall/winter I assume) and I’m not sure how long it takes but with all the twists and turns, and the locks, I’m sure it takes a little while.
I’ve Fished for salmon on Sebago a few times, haven’t gone home skunked. Not sure where you’re from, but we’re talking about Maine/ and probably most of New England—if your not connected to the Great Lakes. So in my opinion and experience, the salmon(and most rainbow fisheries) sizes are somewhat comparable to the bass up here. 1-2lbs is common, 3-4 is Great, 5+ exceptional. There’s no doubt there is exceptional fish In Sebago, of all varieties, but I wouldn’t expect trophies without putting a lot of time in.
Most of my experience looking for salmon/trout in lakes is in the spring or later in the fall. Steep drops to deeeep water preferably near tributaries, deep water bottlenecks, are good places to start, Sonar is pretty much a must-have if you’re new to an area. Assuming you plan to troll
start a thread in the “other species” forum if you need anyone to elaborate on gear, techniques, etc