Pre-checking notes
This is Wahta Mohawk Researve on both sides but if you go west and take the first left (south) onto Kamien-Tara Ohaha road it goes to the river (unnamed on Google) The boat launch is on General Access Crown Land ("GACL") If you paddle west almost every where is open land. The google picture does show some rapids.
The map shows the coastline along the river is private but google does not show any houses or built structures. Look along the south side of the river for a portage trail at about 600 metres west on the river Lunnen lake should be just a 400 metre trail. .
Most of Gray and Lunnen lake shore looks private. However at the north and south end of Lunnen is GACL
For Grey lake and paddle to south end there should be a river and everywhere is GACL including the next large un-named lake and Herdman Lake.