River Ottery

The River Ottery (Cornish: Otri) is a small river in northeast Cornwall, England, United Kingdom. The river is about twenty miles (32 km) long from its source southeast of Otterham to its confluence with the River Tamar at Nether Bridge, two miles (3.2 km) northeast of Launceston.

The headwaters of the River Ottery are within the civil parish of Otterham but formerly came under the parish of Forrabury and Minster. In 1311, the rector of that parish wrote: "..the river Ottery takes its rise in this parish and flows to Canworthy Water and so by Yeolmbridge to the river Tamar."

With its tributaries, the River Ottery forms a major sub-catchment of the Tamar system, draining 48 square miles (120 km²) of north Cornwall. The Ottery's catchment area is within the Carboniferous geological formation known as the Culm Measures which stretches from Dartmoor to north Devon and across northeast Cornwall as far west as Bodmin Moor.

The infant river initially flows north until it reaches the hamlet of Trengune. From here it adopts an east-southeasterly course which it follows to its confluence with the River Tamar.

The largest tributaries to the River Ottery are Caudworthy Water and Bolsbridge Water which join the Ottery from the north and Canworthy Water which joins from the south.

The River Ottery system was severely affected by flooding in north Cornwall on 16 August 2004 when up to eight inches of rain fell during a single afternoon. The Ottery headwaters at Marshgate and Otterham were the most severely affected.

The river flows through an isolated area of mixed farming and the only riverside settlements of any size are Canworthy Water and Yeolmbridge.

The Cornwall Rivers Project notes five Sites of Special Scientific Interest (SSSI) in the Ottery catchment including the Ottery Valley SSSI which has 33 hectares of increasingly threatened culm habitat and Kernick and Ottery Meadows SSSI, also noted for its biological interest.