River Calder, Renfrewshire
The River Calder is a modest river within Renfrewshire, and one of many British rivers to bear the name "Calder".
The river rises in the hills to the east of Renfrewshire and for the first two miles of so of its length it forms the border between Renfrewshire and Ayrshire, whereafter it enters Renfrewshire entirely for the rest of its course.
The only significant settlement which the river runs through is Lochwinnoch, just above the point where the Calder discharges its waters into Castle Semple Loch, which in turn drains out into the Black Cart Water.