This part of the complex water supply system at Rhosydd slate quarry consists of two small reservoirs and the remains of leats between them and to the waterwheels powering Level 9 mill (NPRN 408866) and Level 9 adit haulage (NPRN 40601). The upper reservoir was probably constructed c1859 to serve the mill, the water carried in a wooden trough along a ledge and over stone pillars to the wheel at the south-west corner of the old mill. About 1870 the water was diverted through a new wooden leat to drive the haulage wheel outside Level 9 adit. Later again the lower reservoir was constructed on the rocky bluff overlooking the 9 adit and the bottom of the lower Level 4 - 9 incline (NPRN 408863). Water was transferred from the upper to the new reservoir by a small wooden leat supported on iron rods. These supports and the low pillars which supported the 1870 leat still survive.
W J Crompton, RCAHMW, 30 July 2009.