Minllyn is a slate and slab quarry (nprn 310049) begun in the C19, the most productive phase of which began after the Carlyle Slate & Slab Company was formed in 1872. Work ceased in 1924. Water was collected from the hillside for powering mill machinery at the quarry site and at the foot of the hillside in Minllyn hamlet. The reservoir was fed by a leat (nprn 527529) from Nant Minllyn and, at least in its latter stages of use, channelled water to an engine house by means of an iron pipe (nprn 527468). The reservoir dam is formed by earth and stone banks up to 3m wide, oriented NE-SW, the ground falling steeply to the SSE. The reservoir is approximately 28m long and up to 8m wide, narrowing at the ends, 0.6m deep and retainaing water to a depth of 0.2m.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 22/12/2012.