The North Fork is also a very nice dry fly river, with a variety of notable hatches occurring throughout the season. Here's the breakdown. Darker colored caddis imitations work best in the Spring and Fall, with lighter colors working best in the Summer. Starting in late Spring and stretching through much of the summer, you'll see tan mayflies (#12-#14 is about the right size) and a big black stoneflies (#6 works well) will be in the air. And, finally, you'll see some good Trico hatches in late summer and into the fall. That's not so difficult, is it? If you're a nymph fisherman, it is much simpler: focus on the larger patterns in sizes 6 through 12 and you'll do fine. Black Wooleys and Rubber Legs are popular for imitating stoneflies, but an actual fly tied to imitate will really knock em' dead at times. But when the fish aren't grabbing the whopper flies, the standard back-ups will certainly produce -- hare's ears, pheasant tails, various midge patterns, scuds, and the like. And then there are the BIG FISH hunters, who love aggressively stripping ginormous streamers.
To give you a final qualifying argument about the quality of this fishery, it's the only trout stream in the state that has both a Blue Ribbon area AND a Red Ribbon area.