Several rivers close to Matawa communities are mentioned as potential sources of hydroelectric power in this assessment. On page E-4 you will see the Attawapiskat River being listed as one source of hydroelectric power for the Ring of Fire, whose price tag is close to 172 million. On pages E-4 and E-5 you will also see many of the Matawa communities listed, including Webequie and Marten Falls, along with their respective rivers that may be able to supply them with hydroelectric power. All in all the total price tag for all 5 Matawa communities closest to the Ring is approximately 526 million dollars; at a quick glance. 698 million if you include the Ring of Fire.
https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.owa.ca/wp-content/uploads/2017/01/NorthernHydroFinal-Executive-Summary.pdf&ved=0ahUKEwi5hZPUqpXYAhUd3YMKHU0HBvoQFghkMA4&usg=AOvVaw2N1672kal7YOHOzORCFMz2
TM.