In the late 1990's there were two deaths by drowning at the Parkhill Dam. Don't take unnecessary risks, particularly during moderate or high flows or winds.
I have identified three river exit points which may be used for this portage. Each of these is on the west side of the river, the right bank when paddling with the stream.
B1 is about 300m upstream of the railway bridge at the Cambridge Rowing Club. This is an easy exit point onto mowed grass, perfect place for a resting spot or a picnic lunch. This is a good exit if flows are high. Walk along the gravel road until you get to the trail and then follow the trail which will eventually lead to the bridge. Take the ramp on the downstream side of the bridge and re-enter the river at B5. Overall portage about 1000m.
B2 is about a 100m downstream of the railway bridge. This has some of the advantages of B1, but shortens your portage slightly. Re-enter at B5. Overall length about 600m.
B3 on the northern tip of the island about 50m upstream of the dam itself. This exit point is not recommended for inexperienced paddlers, though for others it is a good exit point to use during low flow conditions. In less than ideal conditions you run a real risk of getting swept over the dam. Take the stairs down at the south end of the island and re-enter at B4. Take care to avoid the boil and the bridge abutments. Overall portage about 75m.