I highly suggest doing this run in the spring when the water is higher or after a few days of rain. I doubt the river is passable any other time of the year. Ideally, you would go soon after the annual Jock River Race as they clear the river of debris and ensure it is passable.
From the put at Munster Rd the first take out at Joy's Rd is just short of 10km. If you take out in town it is closer to 13km.
This container was originally Jock River - Itch (GC87QVY) but it got archived due to its' location. I moved it and now it is Still Itchy.