Mynydd Epynt is an upland area of
Mid Wales within the county of
Powys,
Wales. It is bounded to the south by the upper section of the valley of the
River Usk, and the
Brecon Beacons National Park. It is bounded to the north by the valley of the
Afon Irfon and to the east by the valley of the
River Wye. Its western boundary is less distinct but lies eastward of the
A483 Llandovery to
Llanwrtyd Wells road. Its character is that of an extensive though dissected moorland plateau lying between 400 and 450m above sea level and whose highest point of 478m (1,568 ft) is reached at an unnamed rise at OS grid ref SN 961464. The south-western part of Mynydd Epynt is known as
Mynydd Bwlch-y-groes. The area is drained by several southward-flowing rivers which empty into the
River Usk. These include (from west to east) the Cilieni,
Nant Bran,
Afon Ysgir (with its two headwaters the Ysgir Fechan and Ysgir Fawr) and
Afon Honddu. The Duhonw drains north-eastward into the
River Wye. The highest point is a
Marilyn (having
topographic prominence of at least 150m).