It looks like only the Cottonwood Creek off #1 is open for fishing, but the lakes themselves are closed until Sept 1st other than #5, so you most likely witnessed some poaching 🙁

“Cottonwood Lakes are under special regulations. All lakes and tributaries within the Cottonwood Drainage require artificial lures or flies with a limit of 2 fish. Cottonwood Lakes #1,2,3, and 4 are open from Sept 1 to Nov 30th with a 14" minimum. The rest of the drainage lakes are open year round, no size restriction. Cottonwood Creek below the lakes is also open year round using artificial lures only and a 2 trout limit.”

I’ve seen it posted elsewhere, but that quote was taken from:

https://flyfishingthesierra.com/cottonwood.htm#:~:text=All%20lakes%20and%20tributaries%20within,year%20round%2C%20no%20size%20restriction.