Put in at the cartop access on Rte. 117 in Lancaster and paddled 8.9 miles to the take out in Shirley/Devens. River was a little low but still ok. Lots of downed trees through the first half, through Bolton Flats/Oxbow wildlife Reserve. Some minor portages and a large beaver dam. Second half the river widened out a bit and there were far fewer obstructions. Trip took about 3 1/2 hours. Saw some Great Blue Herons and a small male deer.