Water flows into the Grahamstown Dam from the Williams River, upstream from the Seaham Weir, which limits the inflow of tidal seawater; via Balickera Canal and pumping station, which are used to transfer water from the Williams River to Grahamstown Dam.

[1] The storage was formed by building an embankment across the outlet of a natural depression known as the Grahamstown Moors.

Construction began in 1955, and although all the elements of the entire scheme were not completed until 1965, water was first supplied in 1960 during the severe drought from 1960 to 1963.

[2] The dam wall consists of 2,124 cubic metres (75,000 cu ft) of earthfill with an internal earth core.

At 100% capacity the dam wall holds back 190,000 megalitres (6,700×10^6 cu ft) of water.