Although Bateman does not appear to have been involved during the actual construction, his specification for building the dam has been preserved by James Cropper of Burneside Paper Mill. It specifies that the clay core was to be built up in layers, each thick, and that complete layers should be finished before work started on the next layer. The clay was to be soaked for 12 hours, and then cut into blocks, which were to be worked into the layer below by treading it. The earth dam was to be made of concave layers, thick on the upstream side, and twice that thickness on the downstream side. Material for the upstream side was to be adhesive, and watered in to become nearly waterproof, while the downstream bank was to be built of dry or stony material. The dam had a slope of 1 in 3 on the upstream face and 1 in 2 on the downstream face. A central clay core was thick at the crest of the dam and thick at the bottom of the dam. The upstream face was covered in stone cladding, while the outlet pipe ran through the bottom of the dam with a valve house on the downstream side.