Mooi River (Vaal)
|Name origin: Mooirivier meaning 'pretty river' in Afrikaans|
|- location||SE of Koster|
|- elevation||1,550 m (5,085 ft)|
|- location||E of Stilfontein|
|- elevation||1,305 m (4,281 ft)|
The Mooi rises near Koster and flows southwards. During its course it flows into the Klerkskraal Dam, Boskop Dam and the Potchefstroom Dam. After crossing the town of Potchefstroom it bends southwestwards, shortly bending westwards before it empties into the Vaal River near the border with the Free State, about 15 km east of Stilfontein.
Its main tributaries are the Wonderfontein Spruit (Mooi River Loop) and the Loop Spruit.
In November 1838 Voortrekker leader Andries Hendrik Potgieter and his followers established the first permanent European settlement north of the Vaal by the banks of the Mooi River, founding the town of Potchefstroom. The city was named in Potgieter's honor and was the capital of the former South African Republic until May 1860, when the capital moved to Pretoria.