Dig around these forums and the various websites of local fly shops like Keine's or American Fly Fishing for some great advice and good fly choices. When it comes to specific holes, a lot of us worked hard to find the best holding areas, and with a small river like Putah that gets so much pressure from Bay Area anglers, you will find a lot of the members of these forums to be stingy about handing out information freely and in an online setting. That being said, a little basic info won't hurt.
Small stuff works best here, so you should be mostly slinging flies in sizes 16-24. Flip a few rocks some time and see for yourself how small the bugs are up here. If you tie on tiny midges or small baetis imitations, you're usually in business any time of year. The midges are pretty much ever-present. But the most important thing up here is getting to the bottom and having a good dead-drift. Putah fish are choosy and spooky. This is an educated class of trout very used to dealing with fly anglers, and they've seen a lot of flies over the years. Get yourself some light tippet in 5 or 6x. Fish can be caught with drys or just subsurface, but the name of the game here is primarily nymphing.
With all that in mind, hit the water. Explore a bit. There's plenty of good water at Putah. And all different types. You can find riffles, runs, glides, pocket water, long deep pools, and frog water. Though the latter two can be difficult to fish from shore. With this river, and just about any other I can think of, there is no substitute for time spent on the water. Another good tactic is to speak with other fly fishers on the water. We're usually a nice, friendly bunch and more than willing to discuss the finer points of our sport with newer folks.
thanx for the help. i will be heading out tomorrow and see what i can do. from trying to fly fish i have to say i suck at it. so if i catch anything i will be impressed. but i guess it just takes time
i need to get a license tomorrow preferably someplace that opens early. i didn't expect to still be in cali by now so i didn't get one. so anyone know a good place
I'm new to the area/sport as well. Thinking about taking a ride out to the creek this evening and exploring. Any suggestions on best places to park/explore? From what I can tell, the river doesn't look like it is wadable in most areas. Are there hiking trails along the banks? Any private property I should avoid?