The Piashti River is made up of a series of lakes joined by narrow, fast flowing channels. It has a total watershed area of 386 square kilometers. The river ends its course in the Gulf of St. Lawrence in Baie-Johan-Beetz, a village located 66 kilometers east of Havre-Saint-Pierre.
About two kilometers from its mouth, the river pours into a large lake over a spectacular waterfall. This body of water, called Salt Lake, is fed by fresh water from the river and by salt water from the Gulf of St. Lawrence during high tide. The lake provides an abundance of aquatic vegetation and is home to several seabird species. The migratory bird banding station used until 2004 had the largest concentration of green-winged teal ducks ever seen in North America. There are also seven birds of prey species found in the area, including the swallow-tailed falcon and bald eagle.
The water of the Piashti River is very transparent, but the riverbed is dark like most other rivers in the region. The bottom is made up of gravel and large pebbles. Salmon can only make it up the Piashti for about 6 km. Brook trout, arctic char, landlocked salmon and American eel are among the other species found in the river.
The Pourvoirie Baie-Johan-Beetz Outfitter holds exclusive fishing rights on both Salt Lake and the Piashti River. There are 8 salmon pools scattered throughout the area. Sportsmen and women catch salmon that weigh an average of nearly 6 lbs on the Piashti River, either wading or fishing from a boat.