Thanks for the replies. Just some additional info on this mystery fish:

- the meat was a very pale pink, not deep orange like a fresh fish out of the salt

- it had very small not-yet-developed egg sacks. Each skein was about the size of a fat toothpick

- so....with the Cedar hatchery not producing hatchery steelhead, and with the local hatchery winter run ending weeks/months ago, by process of elimination I guess the remaining possibilities are:

- hatchery smolt that found it's way into the lake and grew to 16 inches?
- early hatchery summer run jack (jill) that strayed into the lake?
- post-spawn downriver hatchery fish (small adult hen?) that wandered into the lake from some other system?
or .... ?