The Upper Harricana aquatic reserve is located between 48°46’ and 50°14’ north latitude and 77°58’ and 78°58’ west longitude. Most of the aquatic reserve lies within the Baie-James Municipality, in the Nord-du-Québec administrative region.
The southern boundary of the aquatic reserve is situated approximately 25 km north/north-east of the town of Amos.
The proposed aquatic reserve covers an area of 177.2 km2. It forms a corridor that takes in a 200-metrewide strip of land on either bank of the Harricana river, protecting the main bed of the river and riparian habitats over a distance of approximately 190 kilometres. To the north-east, the aquatic reserve is bounded by the Muskuchii hills biodiversity reserve.