a fish ladder was added in 2003, to allow migrating fish to access the upper river. Many of the building still exist, some distance to the south of the weir, including a casting house, a workshop, a tinning house, a smithy, a rolling mill, and the retaining wall for the leat. The leat had seven sluices with gates to feed the works, but all have been bricked up. Diversion in Cardiff In the early 1840s the South Wales Railway was trying to find a suitable site for a railway station, but the area that is now Cardiff Central railway station was prone to flooding. At this point the main route of the Taff was around Cardiff Castle and down what is now Westgate Street, with the lands where Cardiff Arms Park and the Millennium Stadium are now sited tidal flats which were prone to flood. Isambard Kingdom Brunel's solution was to divert the Taff to the west, creating a larger and safer site for the station. The station was opened by the South Wales Railway in 1850. Tributaries Nant Ffrwd Underneath the Cefn Coed Viaduct, the Nant Ffrwd, a tributary that runs eastward in a deep wooded gorge before flowing into the Taf Fawr above the confluence with the Taf Fechan, emerges into the river from a deep, narrow gorge. Nant Morlais and Nant Rhydycar The Taff continues south through the centre of Merthyr Tydfil, where it is joined by the Nant Morlais which emerges at Abermorlais from a culvert in the east bank. Just south of Merthyr weir, the Nant Rhydycar joins. Taff Bargoed, Cynon, Nant Clydach and Rhondda South of Merthyr, the Taff begins to meander its way between Pentrebach and Abercanaid and through Troed-y-rhiw, Merthyr Vale and Aberfan towards Quakers Yard. Here, the Taff Bargoed, Nant Mafon and then down into Abercynon in the Cynon Valley where the Afon Cynon merge with the Taff and, slightly further downstream the Nant Clydach joins. At Pontypridd it is joined by the Afon Rhondda. From Pontypridd, it runs roughly south before arriving at the northern boundary of the city of Cardiff. Mouth of the Taff In Cardiff, the natural course of the river was changed during the 19th century; from Cardiff Castle it now follows an artificial riverbed west of where it previously flowed, following a path through Bute Park, past the Cardiff Arms Park and the Principality Stadium. The