The
River Gwydderig or
Afon
Gwydderig in
Welsh is a
tributary of the
River Bran (Welsh: Afon Bran).
It rises as the Nant
Gwydderig on the southern slopes of Mynydd Bwlch-y-groes, about 3 miles
(4.8 km) North of the small village of Llywel
, Powys
.
The
A40 runs next to the river from Llywel as
far as Llandovery
, Carmarthenshire
.
The Gwydderig crosses the boundary between Powys and
Carmarthenshire at the village of
Halfway.
It joins
the Bran in Llandovery, Carmarthenshire, about 1.5 miles upstream
of the confluence of the Bran with the River Towy
. The River Gwydderig therefore forms part of
the Towy's catchment basin and
drains into the Bristol
Channel
at the Towy estuary.