Although the spoken form in the localNorth Wales dialect is Ogwan, and it has also recently been shown that Ogwan is an original form of the name, the form Ogwen is believed to have been mistakenly adopted as a kind of back-formation, because many words ending in -en become -an in the north Wales dialect. The name of the river is recorded as Oguanw in a poem in the Hendregadredd Manuscript. The name is probably a compound word: og + Banw 'piglet' = ogfanw. The precise meaning of og is less clear, but it may either be cognate with the Irish Tír na n-Ógor else derive from the Proto-Indo-European *oku.
Waterfalls
The Ogwen emerging at the western end of Llyn Ogwen immediately descends cataracts and waterfalls, known as Ogwen Falls in English and Rhaeadr Ogwen in Welsh, before continuing in a north-north-westerly direction down the glaciated Nant Ffrancon valley.
Re-Engineered
In the 1950s and 1960s, this stretch of the river was re-engineered to try to help drain the adjoining farmland. However, the beneficial effects were not significant and the ecological damage was great. In the 1990s, the Environment Agency, working with partners including the Countryside Council for Wales and farming groups, re-engineered the river to recreate pools and riffles with the intention of allowing the river to re-gain its original form and diversity of wildlife. As the river continues northwards, it passes close to the great waste tips of slate produced by the Penrhyn slate quarry. A dam was built in the Afon Ogwen at Ogwen Bank, in the early 20th century, to raise the level of the river in order to provide water for the use of the nearby Penrhyn Quarry and then past a caravan site, Ogwen Bank, where the remains of a long abandoned watermill and mill pond still exist. Passing Braichmelyn village on its eastern bank, it is joined by the substantial tributary, the Afon Caseg, which drains a large area of the Carneddau mountains. The course turns slightly more westwards as the river passes through Bethesda and becomes progressively more wooded and more deeply cut providing some white water conditions enjoyed by canoeists. The widening river then follows an abandoned railway line through a woodland valley crossing under the main north Wales coast line and the A55 before discharging to the Menai Strait at Aberogwen, near Bangor.
