Greg,
Pike wise, the prime water starts around Scruton / Morton Area and below all the way down to its confluence with the Ure. In terms of what clubs have what, in broad terms:
Northallerton AC - 4 or so miles above and below morton
Middlesbrough AC - Stretches at Gatenby, Maunby, Holme, Ainderby Quernhow and Skipton Bridge
Bradford No1 - Stretches at Gatenby, Maunby, Pickhill, Topcliffe (not the prime bit), Asenby (5 pegs or so), and then their prime water at Thornton Bridge (above and Below)
Leeds & District - A short bit near Skipton, Topcliffe, Asenby, Helperby and Myton
I'd suggest these as your prime choice for Swale water - but a fair few other clubs have stretches here and there (Bradford City AA being an excellent example). It may be better going for Bradford or Leeds as they give you plenty of other options on the Wharfe, Nidd, Ure etc
Good luck!