The water could be clear. The fish there see a LOT of flies and can be picky, so you probably do not want to use larger than 7x tippet. I would use flurocarbon. Some use different brands of flurocarbon. So if you aren't catching them on one brand...switch to the other. The middle of the week is less crowded, so always a good time to go. Small flies work better that time of the year.
I would recommend stopping by Larry's Fly Shop as they know what will be working well when you are there.
There are fish all over the place. I think as with anything in hunting or fishing, if you fish an area where you don't see as many people, the fish are not as disturbed. They are wild even though people crawl all over them in the park.
Wet flies will produce a more especially early in the year. It is always fun to catch them on some dries.