Here’s a thought to throw out there that always gets me is the great Allegheny river. There are thousands of trout being thrown into creeks that flow into the river. Now for years I’ve fished the river from dam to city. Never seen or heard of trout being caught in that river except for below the dam. The fish comm.. stocks fingerlings there and the trout stay in that section of Warren. Think the oxygen and water’s staying cold enough. From a bottom fed dam.
I don’t have anything specific to add to what you said, however I‘m always interested in any discussions about trout fishing in the Allegheny. I grew up in Warren, and as a young kid I fished extensively around there before the dam was built beginning in 1960. My family moved away in 1960, but I returned to live there again for a short time in 1965-67, just after the dam was completed.
I don’t remember catching any trout in the Allegheny before the dam was finished. I caught lots of bass, walleye, and even hooked a couple muskies in the river though, and did catch a Brook Trout or two in the Conewango Creek, and was really surprised to get any trout there.
Here’s a picture of the 1956 flood, taken at the intersection of Market Street and Penn. Ave, and I remember seeing several small ponds of water elsewhere in town filled with fish (some were big fish) once the flood water receded.
For several years after the dam was completed, the trout fishing was great in the river, possibly even better than it has been since. They even let you crawl down onto the dam abutment back then, and the trout fishing right in the discharge was exceptional. I’ve also caught large (and smaller) trout in the river both above and below the tributary streams that go into the river downstream of the dam (as I’m sure you have too) and I suspect a lot of them are, or once were, stocked trout moving into and/or out of stocked tributaries. I don’t recall that there were any trout, even fingerlings, stocked in the river back then, so it‘s logical they they came from from tributaries (being stocked or stream bred).