Stephen,
Your right. The right of way is in the middle, with the creek running alongside.
Have you ever had the chance to walk up Larch? If not it is a definate must. All the ties are still in, and the grade is almost perfect yet. A few remains of the old Alder Springs Trestle can be seen as well.
Needless to say, the Sumpter Valley is a well kept secret, and a beautiful one at that.