Real Answer is No that is why they put them there and in Sprague, because the Eviro wackos on the coast don't want them in the gene pool.
That said I used my useless degree in Geography from EWU to find if they go down Rock creek I think the can get to Palouse Falls and then to the Snake.
My son and I caught a slew of them the last week of Jan, on egg sucking leeches and a full sink fly line on the very far end at the falls. They are small but fought harder than the average Williams Lake Planter. It was fun for what it is. I do bird hunt Escure a lot, and I thought maybe in 2 falls they would run up Rock Creek if they think the lake is the ocean. I don't know. Normally I do the Ronde or Tucannon for a castnblast, but it would be cool if run the river.