Allt Graad (Scottish Gaelic: Allt Grànnda: Ugly Stream) (or River Glass) is a river in Easter Ross, Highland, Scotland. It is named on Ordnance Survey maps variously as Allt Graad and River Glass. It has also been known as the "Allt Grande", and the archaic Anglicization, "Aultgraad".
As of 2011, a hydro-electric scheme is under construction on the Allt Graad. This run-of-the-river scheme is on the lower catchment of the river, next to the Black Rock Gorge. It will be operated by RWE Npower, and have a capacity of 3.5MW.
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