The Black Cart Water is a classic West of Scotland spate river flowing approximately six miles from its source at Castle Semple Loch in Lochwinnoch, Renfrewshire, northeast through the communities of Howwood, Johnstone, and Linwood before passing under the M8 motorway at Blackstoun, where it meets the River Gryfe. It continues parallel to the main runway of Glasgow Airport before joining the White Cart Water near Renfrew, ultimately forming the River Cart. As part of the broader Clyde river system, the Black Cart has undergone a remarkable ecological recovery since the decline of heavy industry in the 1970s, with dramatically improved water quality transforming it into a productive and increasingly popular fishery. A notable feature of the river is a controlled weir at Howwood, which helps maintain water levels at fishable conditions — a significant advantage over purely spate-dependent rivers in the region. Fishing on both banks of the Black Cart Water is managed by the Castle Angling Club, which controls the full six-mile stretch from the Castle Semple Loch catchment to the "Junction Pool" at the confluence with the River Gryfe.