The considerable urbanisation, especially in the 19th century, confined most rivers to rather narrow artificial channels, bordered in places such as Bridgend with concrete flood protection walls.

[2] The River Garw flows broadly north-south and runs through Pontycymer to its confluence with the Ogmore (Ogwr) at Brynmenyn.

The industrialisation of the valley of the Ogmore by mining and heavy industry severely damaged much of the natural environment of the river.

The river does still have some problems though, including its proximity to major industrial plants, insensitive development and invasive weeds.

In recent years UV treatment has been added to substantially reduce the bacterial and viral load of the treated effluent.