The Yealm is a river in Devon in England that rises 430 m (1,410 ft) above sea level on the Stall Moor mires of south Dartmoor and travels 12 miles (19 km) to the sea, passing through Cornwood, Lee Mill and Yealmpton, a mid-sized village with a population of c.2,000 which is its largest settlement, before reaching its estuary which forms a ria bounded on its western side by Wembury.

A deep inlet of this ria forms the waterfront to Newton Ferrers and Noss Mayo on its eastern side.

The harbour authority is made up of representatives from the civil parish councils of Wembury, Yealmpton, Brixton and "Newton and Noss".

The River Yealm may have lost some of this stock of the most-eaten fish in the United Kingdom, but it has managed to retain other important species: it remains a key conservation area.

Here, the River Yealm and its estuary incoming flows keep a well-matched balance, such that the freshwater and seawater mix is in approximately ideal proportions.