It is a true blackwater stream, owing to spruce and hemlock trees in its watershed, the tannins of which impart a tea or amber color to its water.

[9] Here it forms whitewater rapids of Class IV-V+[10] and collects the eight-mile (13 km) long North Fork Blackwater River,[11] which flows past the town of Thomas.

In recent years, the limestone treatment of AMD in the Blackwater River has met with success with the effort receiving an award from the U.S. Office of Surface Mining.

[12] AMD is created when sulfite-bearing mineral strata are exposed to air and rainwater, such as when surface mining occurs.

[16] The five miles (8.0 km) stretch of the Blackwater between the limestone station and the confluence with the North Fork has now become one of West Virginia's premiere catch and release trout streams.