Another way to cast upstream in this type of place is by using an upstream Snap-T. You simply move the line upstream far enough so that the fly is pretty much even with you, this is followed by moving the rod downstream while watching the 'white mouse' (as Simon so aptly names it), and when the 'white mouse' gets even with you, launch your upstream cast. This needs no room behind you at all. And it forms a wonderful anchor. Casts of 80+ feet upstrream are possible with this variation of the Snap-T.