Standing Stone Ck has very limited buffering capacity in the wild trout stretches above and below Detweiler Rn so it’s probably somewhat acidic at times given its location. I recall an early spring acid related fish kill when it was a stocked stream. It supports a respectable wild brown trout population, or at least it did in the late 1970’s.
As a leap of faith, I suspect that the E Br Standing Stone may be somewhat similar upstream from Greenwood Furnace Lake given its proximity.
You can easily find Wild trout survey East Branch Standing Stone Creek on YouTube.