Information comes from Archaeological Assessment of Cilcain Reservoir Discontinuance, Flintshire, conducted by Gwynedd Archaeological Trust in March 2019:

'As specified in data supplied by Stillwater Associates Limited, Cilcain reservoir consists of two separate pools and was constructed in 1896. Cilcain no:1 has an earthfill embankment dam which is 55m in length, whilst Cilcain no:2 has an earthfill embankment with a puddle clay core which is 100m long and 8m high. The inlet for Cilcain no:1 is uncontrolled from the Nant Gain which then feeds Cilcain no:2 via a channel. Cilcain no:2 has a 3m wide spillway and 12? diameter overflow pipe in addition to two other low level outlets which are described as inoperable.'

RCAHMW, 15th January 2020