[1][2] The Klastline River flows through Mount Edziza Provincial Park which lies within the traditional territory of the Tahltan people.

[6] The Klastline River's watershed covers 1,841 km2 (711 sq mi) and its estimated mean annual discharge is 21.5 m3/s (760 cu ft/s).

[7] From its source the Klastline River flows about 5 km (3.1 mi) north to the southern base of an unnamed circular, flat-topped mountain.

The trail enters Mount Edziza Provincial Park at about 25 km (16 mi) where Kakiddi Creek drains into the Klastline River.

[18] The Klastline River has been repeatedly blocked by lava flows from the adjacent Mount Edziza volcanic complex.

Moraine Cone produced a northeasterly lava flow that temporarily blocked both Kakiddi Creek and the Klastine River.

Subsequent etching of new channels around or through the flows by both streams has exposed beds of lacustrine silt where lava-dammed lakes ponded upstream.