I have definatly seen fish spawning in upper walnut. I try not to fish the winter and spring near gravel for this reason don't want to step in a good reed. Some thing that might be neat is if they colsed the upper reach's of the streams to winter and spring fishing maybe above 79 on walnut and a little further on elk. Before anybody goes off the deep end here think about this. The Pa game commision says they stopped the pheasnt propagation program because they could not get wild repduction. Now I will say we have proved them wrong on are farm and neighboring farms. Banding and stocking birds for a few years Now we get a few every year with no bands (we also only shot roosters) 15 non banded birds this year. Just like the fish If you kill alot and destroy nesting habitat how much nautrual repoduction can you expect to get. So I think If you let the upper reaches alone and stay out of the water in spawning areas you could have alot more wild fish. We try not to wade to much in the fall down here just to help the natural repo of the local streams. JMO and please think of this the next time your in one of these areas one wrong step and you might just kill 100 good eggs or more!!!

just to add to my post I didn't walk in the stream I fished, just alongside of it.  If you do venture to a trickle, please try to stay out of the water as its probably not a good idea to tromp in it for the obvious reasons, and beacause the fish are so finicky.  I think its fun to catch big fish in small water it def tests your skills. 

ORIGINAL: TransAmWS6

what about the 6 inch brown, how did it get tehre?

Spoon mentioned NY.
NY does stock 1 and 2 year old brown trout way up the creek in April.  Usually, those brown trout range from 8 to 16 inches.
It wouldn't be impossible that your 6 inch trout is wild. I would guess that it being 6 inches would be about right for a trout nearing one year old in this creek.
 Still, it could even have been spawned wildly from PA browns. Your guess is as good as mine.
 

its like being precise on a spring creek to a skittish trout because theres just really no room for error, you make a mistake and its all over.  Plus, its good practice to keep fish out of snags and such;  ive seen magazines where guys were dry fly fishing for salmon in headwaters that were literally maybe 2 foot across, I dunno just like it. 

Small water fishing is AWESOME. It is one of my favorite challenges in fishing. The fish are ultra spooky, and presentation and stealth are so very critical. I fish some places in central PA where the streams are barely 6 or 8 feet across, but there is trout in them in the 28" range. There is nothing to me more personally rewarding than pulling out a trout of that size in those tiny waters. Make one bad cast, or one step to far, and your chances go to zero in a hurry.