The River Conwy, or, in Welsh Afon Conwy , is a river in North Wales. It rises on the Mignient and moors then flows north through Betws-y-Coed, Llanrwst and Trefriw before reaching Conwy Bay at Conwy.

Geology and Landform

The Conwy is bounded to the East by the rolling ancient mudstone hills of the Silurian period, the Migneint Moors. These acid rocks are generally covered in thin, often acid soils and for large parts of the upland areas the cover is of moor-grass - Mollinia spp and Erica communities. As a result the water entering the river tends to be acidic and often coloured brown with humic acids

To the West, the catchment is underlain by older Cambrian rocks which are harder and the landscape is, as a consequence, more dramatic with high craggy hills and mountains through which the river falls in cascades and waterfalls. Excellent examples of torrential river geo-morphology can be seen at Conwy falls and in the Lledr gorge. The land to the East is highly forested with planted non-native conifers.

The eastern side of the valley is rich in lakes and reservoirs some of which provide drinking water supplies . The rocks are also rich in minerals and there are many abandoned mine site where Copper, Lead and Silver have been mined since Roman times The central river valley down-steam of Betws y Coed is relatively wide and fertile and supports dairying and sheep rearing. In winter time these pastures are used to nurture the sheep brought down out of the mountains to avoid the worst of the winter weather.

Culture and History

At the mouth of the Conwy as it discharges into Liverpool Bay is the town of Conwy with its World Heritage Site castle - Conwy Castle and two famous bridges. One of the earliest road suspension bridges by Thomas Telford now carries a footpath whilst the Stephenson tubular iron bridge still carries the main Holyhead to London railway line.

The scattered communities along the Conwy valley have ancient traditions with archeological evidence of habitation back to the Stone Age. The Romans occupied this area up to 400 AD and there has been continuous habitation since that time.

River Quality

The River Conwy is routinely monitored for quality by the Environment Agency. The river quality tends to be acidic in the headwaters with very low concentrations of the common anions and cations. Whilst conductivity rises as the sea flows towards the sea, the overall organic quality remains very good despite some slight increases in ammonia due to diffuse agricultural inputs.

Biology

The Conwy is noted for its Salmon and Sea trout although increasing acidification in the second half of the 20th century, especially in the poorly buffered upland waters has significantly impacted upon their spawning success. The construction of an artificial fish pass in the 1990s to allow migratory salmonids access to the river above Conwy falls was intended to help mitigate the affects of acidification