Starting in
Cliviger, its source is very close to that of the
West Yorkshire river with the same name, and that of the
River Irwell. It flows northwest through the Cliviger Gorge supplying two fish ponds near Pot Oven Farm, before collecting Green Clough as it passes
the Holme and Black Clough near
St John's Church at Holme Chapel. As the Valley widens, the Calder is met by Easden Clough near Southward Bottom and continues to Walk Mill. At the Cliviger Bridge it passes under A646 Burnley Road and it collects Dick Clough near Barcroft Hall before entering
Towneley Park and being joined by Everage Clough. On the
Burnley side of the park it passes
Unity College and
Fulledge Recreation Ground, and under the Hand Bridge which carries the
A671 Todmorden Road. It flows on the northern side of the town's
Burnley Wood district and through a
culvert in the
Burnley Embankment on the
Leeds and Liverpool Canal and on through the town centre. It is again culverted, first as it is crossed by Centenary Way and then again at Parker Lane, before running under Chaddesley House and Manchester Road next to the Town Hall and
Mechanics Theatre. It is then crossed by Hammerton Street before flowing under the old Empire Music Hall and Cow Lane as it
meanders to the west and is crossed by St. James's Street, then joined by the
River Brun just before the Active Way bridge. Turning to the north and under the
East Lancashire railway line viaduct and through the site of
Burnley College and under the
M65 motorway as it leaves the town. It collects Barden Clough near Royle and is shortly after joined by
Pendle Water at Burnley Wastewater Treatment Works (also known as Duck Pits) on the edge of
Reedley Hallows parish. It is met by Spurn Clough and Moor Isles Clough as it turns sharply to the south west past
Ightenhill and collects Whitaker Clough near
Gawthorpe Hall and continues through the town of
Padiham where it is met by
Green Brook. It is joined by Castle Clough Brook as it passes the old
Padiham Power Station before collecting Dean Brook and then Shorten Brook as it flows past
St James' Church at
Altham. Crossed here by the
A678 Burnley Road, the river turns northwest and the meanders become more pronounced as it is met by Simonstone Brook, Syke Side Brook and then
Hyndburn Brook at Hyndburn Wastewater Treatment Works near
Great Harwood. Continuing its winding route it is then crossed by the
old railway viaduct at
Martholme, and shortly afterward it is joined by
Sabden Brook, just before flowing under the A680 Accrington Road at Cock Bridge. Turning to the north and the back to the west as it is met by Rodger Hey and Egg Syke Brooks and another Dean Brook, it approaches
Whalley. Here it runs over the corn mill weir and under Whalley Bridge before it passes the ruins of
Whalley Abbey, and is then crossed by the red brick
Whalley Viaduct. After flowing under the
A59 bypass, it collects Bushburn Brook and then meets the Ribble near
Brockhall Village. ==History==