Free Stretch Boundaries On The River Tees. Particularly Blackwell, Darlington.

[S.Maclean 94]

Does anyone know what the physical marker is for where the free stretch of Broken Scar around to Blackwell ends and becomes Darlington Brown Trout water? I know it's 1100 feet from the bridge but is there a specific marker, there are old signposts and old fences around that look as though they could've been used.

[Fellman Mark 611]

I was told it’s where the concrete wall starts behind the new houses at Blackwell end