Cardiff Harbour Authority (CHA) is the managing authority for Cardiff Bay under the Cardiff Bay Barrage Act 1993, and was established on 1 April 2000. It took over responsibility from Cardiff Bay Development Corporation and is responsible for the inland bay, Cardiff Bay Barrage, the outer harbour and the rivers Taff and Ely. The harbour authority is part of the City of Cardiff Council and is the statutory navigation authority for Cardiff Bay.

Cardiff Bay is an area and freshwater lake in Cardiff, Wales. The site of a former tidal bay and estuary, it is the river mouth of the River Taff and Ely. The body of water was converted into a 500-acre (2.0 km2) lake as part of a UK Government redevelopment project, involving the damming of the rivers by the Cardiff Bay Barrage in 1999. The barrage impounds the rivers from the Severn Estuary, providing flood defence and the creation of a permanent non-tidal high water lake with limited access to the sea, serving as a core feature of the redevelopment of the area in the 1990s.