A C19 leat marked on the 1891 OS map, approximately 1km long NE-SW taking water from the headwaters of Afon Gamallt below the lakes, probably to the mill at the foot of the incline at Drum Quarry (nprn 536708). At the NGR given it is formed by a ledge 1m wide, while toward the NE it consists of a slight ditch with an upcast bank. It can be followed to the SW almost to the incline at Drum Quarry, from where it appears to have been directed down the hill to the mill.
Other sections of the leat are intermittently visible. A section 90m long NE-SW is visible at SH 7361 4339, where it is reduced to a ledge 1.2m wide. Another section is clearly visible at SH 7375 4355 as a ditch between 0.9m and 1.3m wide, with upcast bank, where it curves round a hill, and then is lost where a stream flowing from Y Garnedd crosses it. Futher to the NE, beyond the stream, another section is visible about 80m in extent curving northwards around a hill as a ledge 1m wide, ending at flatter ground further N.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H & H, 09/01/2014.