The Upper Medway Sub-catchment
The Upper Medway rises in the High Weald in Sussex, and drains the north side of Ashdown Forest before flowing through a largely rural catchment to join the Medway's major tributary, the River Eden, at Penshurst.
The Upper Medway is dominated by clay geology, which makes the river quick to react to rainfall events, and susceptible to low flows in the summer. Mixed agriculture is this sub-catchment's major land use, and its waterbodies range from good to poor status.