Chinook salmon will and do inhabit thin feeder creeks and backponding waters way less accessible to Adult Chinook Salmon due to size requirements. Its not when they are adults, and spawning. Its when they’re at thier smallest, not super strong returning adults. During high water events in the spring, the young Chinook seek those environments around small feeder creeks, and beaver ponding as soon as they can for current escapement as well as food and hiding from predators. As soon as the water recedes, the young will slowly move back into the mainstems.

Non of those young king salmon fry were spawned in these creeks and backwater environments. But they do need access to them certain times of the year, or a lot of fry / pre smolts die...