My primary trout rod is a nymphing 10’ 3wt nymphing rod. But I have been thinking about getting another shorter lightweight rod to cast traditional weight forward fly lines, primarily for small stream fishing, casting dry flies, and even fishing for panfish.
Should I look at an 8’6” 4wt or should I go even lighter?
First off, small as in "small streams" is extremely subjective.
A narrow stream is "small," however if you don't have overhanging trees, rhododendron tunnels or streamside brush limiting your ability to wave around something between 7'6" and 8 foot long, you don't really need to go really short. Many people consider Slate Run a small stream, however I fish there with an 8'0" or 8'6" rod most of the time because the forest doesn't hem you in.
Another thing, small streams usually offer small pools broken up by frequent riffles. That means short drifts that are often spoiled by a current dragging on the belly of your fly line hanging off your tip top if you are fishing a short rod. In these situation you will really come to appreciate a longer rod with longer reach.
That being said, even though I fish rods as short as 5 feet and I fish 6'6" rods a lot on the overgrown places, I still always go with the longest rod I can get away with wherever I fish.
I'll give you a couple of recommendations:
First, do some reconnoitering at streams you want to fish to see how small they really are before deciding on a rod length.
Once you THINK you know the rod you want, try test casting it at the short distances you expect to cast. You may find out the rod doesn't load the way you like making a 20 foot cast. You can improve upon this situation by either fishing a heavier line than is written on the rod blank or choosing a softer action rod.
Fiberglass excels in these situations, especially if you decide to go with a shorter rod. Fishing a short leader also helps a lot because you want as much fly line out past the tip top when casting short. I use leaders around 5-6 feet long when fishing small streams.
Don't worry about what line weight your rod fishes best. First off, wind is usually never an issue when fishing most small streams because of the amount of vegetation around them. Second, you will be casting so short that you most likely will only be presenting a small portion of the line belly anyway.
Most of my small stream arsenal are 3 & 4wts, more because of the smaller reels I can use and have the rod/reel balance I like versus the belief I need something delicate and light.
Have fun!!
.