General trout season in California runs from the last Saturday in April until Nov 15.
The Truckee River has some specific restrictions. You can't fish for something like 1000' downstream from where the river leaves Lake Tahoe. From that point to where Trout Creek enters the river in the town of Truckee is subject to the normal season. From Trout Creek to the Nevada State Line is open off-season to catch & release/artificial lures/barbless hooks only. There is a subsection of water that is restricted to barbless flies specifically.
My understanding is that the state still plants trout for the tourists in the general area from Lake Tahoe to Truckee and then doesn't plant downstream. Consequently, I have never kept a fish out of this river, as they are a wild and naturally reproducing population.
Carson River is another story...some of those hatchery fish have made it into a frypan every once in a while