 The river downstream of the lock is the Richmond and Twickenham reach of the Tideway, a reach of semi-tidal river due to the fact the Richmond Lock and half-tide barrages limits the fall of water thereby maintaining a head of water to aid navigability at and around low tide.Though the weir at Teddington Weir marks the managed river's usual tidal limit, after prolonged rainfall causing very high fluvial flow, specifically at high tide, a higher limit of slack water (stand of the tide) causes eddies to arise as far upstream as the top of this reach, the next lock.The large, bow-shaped Teddington Weir is against the opposite bank.