19 Looking north along the dyke we see Daer Reservoir and that is Tinto Hill in the distance up in Lanarkshire. I grew up in Glasgow and it was commonly held there that the source of the River Clyde which runs through Glasgow was Tinto Hill, but as you will see if you try this link, Daer Water has at least part claim to that honour along with Potrail Water which rises at the back of Durisdeer Hill (east side of it).
There is also a saying that the Rivers Tweed, Annan and Clyde all rise from the same hill. There is a Clyde Law (OS Ref. NT027171) which is certainly near the sources of the Tweed and Annan Rivers though there is a short descent and ascent before you get there from them - so there is a wee touch of poetic license here then.
Clydes Burn runs west off Clyde Law, runs past a place called Little Clyde and joins the conjoined waters of Daer and Potrail just south of Elvanfoot (OS Ref. NS963155). The first place that the Ordnance Survey "Landranger" map uses the name River Clyde is between Crawford and Abington and they still call the conjoined waters of the Daer and Potrail "Daer Water" after the conjunction. So the official source remains a bit of an enigma and you can take your pick with what you want to believe. Click here if you want to see a shot of the upper reaches of the Potrail above the Dalveen Pass.
The River Clyde was certainly very important indeed to the development of Glasgow. They have another saying in Glasgow, that "Glasgow made the Clyde and the Clyde made Glasgow" The townspeople dredged the river for the boats and the trade from the boats and the shipbuilding made Glasgow "the second city of the Empire" - when there still was an Empire! Here is another site you might like to look at in connection with the Daer Reservoir.