What do you (and anyone else) think caused the increased wetness in that area?
It happened so suddenly from my perspective that it hard to rule out that the massive rain events of 2004 & 2005 may have dislodged tons of silt because I've fished the Letort since the 1970's and other than the fish kill in 1981, conditions until then were pretty stable. Yea, the fishing was up and down but the Letort was never a place where you expected to catch a dozen fish every outing...
HOWEVER, things haven't changed radically along the entire length of the stream, in other words the banks are just ridiculously muddy in some areas, most notably where I mentioned.
Into the 1980's and 1990's it was relatively easy to walk from the lower RR trestle just above Letort Park all the way up to Bonnybrook Road on the Spring Garden Street side of the creek. That's partly because of the work done by Fox, Marinaro & the Letort Regulars and the stream saw a LOT more pressure back then so the trails were well worn and easy to follow.
In addition, myself and others spent time cutting back stuff like multi flora rose so the trails were passable while others put rocks or stepping stones in the marshy areas. There were also secondary trails that enabled you park either at Vince's Meadow or elsewhere and walk right down to Otto's, just below Otto's or right to the Barnyard without disturbing others fishing between points A, B or C..
Heck, I used to park right by the quarry gate and walk right through thier propery to fish and they never said boo. I doubt that would be the case today... The trail maintenece isn't happening today at all, so the trails are overgrown to the point of being impassable and invisible.
As far as silt goes; gravel areas I know intimately are still there, although Fox, et al. had a lot to do with exposing some of them initially.
A good silt test I'm willing to let someone else try is to see if you can still cross the stream at two places between the Vince's Meadow and Otto's. At those spots there was some some gravel and larger rocks that permitted those in the know a way to cross to the other side without walking all way to one or the other RR trestles.
Coincidentally at one of those spots I used to catch a VERY, VERY small Trico hatch and would always catch a few dinks every outing...
Another silt test to ask the locals what the status is of the Trico hatch below Shady Lane. I haven't fished it in decades so I don't know.
As far as development goes, there is a TON more in the vicinity of Carlisle, but along Spring Garden Street to the right branch (AKA, "UNT to Letort Spring Run") headwaters, things are are pretty much unchanged and these headwaters now are protected. The property from Trego's upstream to the mainstem headwaters isn't really developed much more either.
The rest of the property on both sides of the stream in the FFO section are pretty much the same as they were the last 20 years and the Union Quarry is still in operation.The only exception other than the Home Depot is a $#!+load of newer townhouses built beside the Home Depot. Like Home Depot, I would HOPE they had to do something special with their storm water, but until someone tells me differently, I haven't seen a finger of blame pointed their way.
The bottom line is as Vince Marinaro said, the Letort would benefit from river keepers like they have in England who cut back weeds, maintain trails and keep the stream in shape. Vince & company did a LOT of that with much of the work being done just before wrote "In the Ring of the Rise."
But those guys were older in those days and while CVTU picked up some of the slack, it ain't even close to the way it was when I made my first pilgimage as a wide eyed teenager. It really saddens me because I fished there an awfult lot for someone who lived anywhere from 90 - 190 miles away...