This post is a little late so forgive me.
In early October I went to Chopaka and threw some streamers and nymphs around
Of course I caught some nice rainbows and smallies, its too do hard this time of year you know? What was interesting though were the two Lahontans I landed. Now I know it sounds funny but I landed two Lahontans. I'm not kidding these fish were text book lahontans.
has anybody else caught Lahontans at Chopaka?
I've never caught a Lohontan in Chopaka, but I have caught a few cutthroat over the years. My understanding is that before they started planting it, Chopaka was a native cutthroat lake & that they spawned in the outlet creek.

I wonder how Lahontans got up there. Maybe somebody caught a few in Blue Lake & transported them. Maybe the WDFW did it - either on purpose or accidental.
I am confused just like you. I have caught what I thought were Cutts in all of the lakes you mention and more. Chopaka, Blue (okan), Dry falls, Rockyford, Homestead, Halfmoon, to name the majors. Some of these fish looked to be pure Cutthroat, and some looked RB with the slash, very obvious slash. I dont know if these are hybrid of somesort, or leftovers mixed into plants??? The fighting ability of some of these fish was very much stronger it seemed to me. I have caught them in sizes from 8 inches to 5 lbs, so it appears that they are planted regularly. I have threatened to talk to the local biologist on the matter, but just cant bring myself to do it. I guess now would be a good time, hopefully they are next to the fire at the moment.
I wasnt surprised to see your post, it is a good question.
I guess this doesnt add to the answer, just brings up more confusion, so we will see what we can come up with.