The Shannon hydroelectric Scheme was a major development by the Irish Free State in the 1920s to harness the power of the River Shannon. Its product, the Ardnacrusha power plant, is a hydroelectric power station located near Ardnacrusha within County Clare approximately 2.4 kilometres (1.5 mi) from the Limerick border. It is Ireland's largest river hydroelectric scheme and is operated on a purpose built headrace connected to the River Shannon. The plant includes fish ladders so that returning fish, such as salmon, can climb the river safely past the power station.

The River Shannon is the major river on the island of Ireland, and at 360 km in length, is the longest river in the British Isles. It drains the Shannon River Basin, which has an area of 16,900 km2 (6,525 sq mi), – approximately one fifth of the area of Ireland.