The Harrison River is a short but large tributary of the Fraser River, entering it near the community of Chehalis, British Columbia, Canada. The Harrison drains Harrison Lake and is the de facto continuation of the Lillooet River, which feeds the lake.
The Harrison is navigable, although in the days of the Fraser Canyon Gold Rush of it was necessary to dredge the sandbars at the confluence with the Fraser, which were known as "the Riffles", and also as "the Falls of the Harrison". Dredging of these shallows was needed to make the river navigable to Harrison Lake, at the north end of which the townsite of Port Douglas was established as the port for the Douglas Road to Lillooet in the upper Fraser Canyon, in order to bypass hostile territory in the lower Canyon (see Fraser Canyon War).