I found this article on gorp.com, and it looks pretty informative:A Golden Opportunity
Trout Fishing at Inyo's Cottonwood Lake
By Matt Purdue
Looking at DFG rules, it looks like you can fish between July 1 and Nov 15. The lakes are catch-and-release except Cottonwood Lake 5, where there is a 5-fish limit on that lake. They restrict bait to artificial lures/flies with barbless hooks.
Maps have the lakes numbered differently, (with one showing two as "Lake 5". But more show the northern-most (farthest away) lake as #5. I would think lake 4 would be the best fishing, since it is farther away and it is still catch-and-release.
If you end up going, would sure like to hear how successful the fishing is.