River Taff

The River Taff rises in the Brecon Beacons as two separate streams, the Taf Fechan and the Taf Fawr, which join north of Merthyr Tydfil. It flows south through Pontypridd and Taff’s Well, where Wales’ only thermal spring bubbles up. The river passes under the M4 motorway before winding past Cardiff suburbs like Radyr and Llandaff. Near Cardiff Bay it meets the Bristol Channel after collecting tributaries such as the Rhondda and the Ely. The waterway supports salmon, sea trout and eels on their migrations.

The Taf Fawr’s upper catchment covers 4,000 acres and feeds reservoirs built by Cardiff Corporation in the 1880s and 1890s. Cantref Reservoir was finished in 1892, followed by Beacons Reservoir in 1897, and later Llwyn-on Reservoir in 1926. The Cefn Railway Viaduct, with its fifteen brick arches, crosses the river near Cefn-coed-y-cymmer. On the west bank stands a leat built in 1766 for Cyfarthfa Ironworks, fed by a stone weir and cast-iron sluice.

The Taf Fechan supplies water to Merthyr Tydfil and passes through three reservoirs. Lower Neuadd was completed in 1884, Upper Neuadd in 1902, and Pontsticill in 1927. Pontsticill’s dam is 110 feet high and holds 3,290 million gallons. A Gothic-style valve tower and outflow funnel are listed structures beside the reservoir. The river then continues through wooded valleys towards Pontypridd, carrying its flow to Cardiff Bay.