From Digley Reservoir, the river flows north-east through Holmbridge and Holmfirth.

It flows NNE to Thongsbridge and Brockholes then north to reach Honley, Berry Brow and Lockwood.

It wends northwards and joins the Colne (one of five rivers of that name) just south of Huddersfield town centre at Folly Hall.

Thus in February 1852, the reservoir broke its confines and flooded the valley as far as Holmfirth.

The underlying bedrock was laid down in the late Carboniferous period and is primarily of Millstone Grit with some sandstone interspersed with thin coal seams.