| Key functions | Non-tidal river (above Teddington Weir) | Tidal river (London area) | Tidal river (below London to sea) | Central Government |
|---|---|---|---|---|
| Conservancy of River | Thames Water Authority (TWA) (from 1 April 1974) | TWA (from 1 April 1974) Port of London Authority (PLA) retain some conservancy duties (oil; floating debris) | Regional Water Authorities (RWAs): TWA, Anglian Water Authority, Southern Water Authority | Department of the Environment |
| Flood Protection | TWA (Thames and other 'main rivers') Riparian local authorities | Greater County Council (GLC) (for 'London Excluded Area'), including work on Thames Barrier Riparian local authorities | RWAs Riparian local authorities | Dept of the Environment. Ministry of Agriculture, Fisheries & Food (MAFF): Land Drainage & Water Supplies Division |
| RWA-run Regional Land Drainage Committees | ||||
| Land Drainage | TWA (Thames and other 'main rivers') | GLC ('London Excluded Area': 'main metropolitan watercourses') Ordinary / non-main watercourses: GLC & London Boroughs | RWAs (main rivers) and oversight of Internal Drainage Boards (ordinary watercourses), e.g. Lower Medway IDB and Upper Medway IDB | MAFF: Land Drainage & Water Supplies Division |
| RWA-run Regional Land Drainage Committees | ||||
| Navigation / Pilotage | TWA | PLA Pilotage: Trinity House | Dept of the Environment | |
| Pollution Control | TWA | TWA | RWAs | Dept of the Environment |
| Port / Harbour Authority | Not applicable | PLA | Dept of the Environment National Ports Council | |
| Recreation | TWA | GLC | RWAs | Dept of the Environment. Water Space Amenity Commission |
| Riverside Planning | Riparian local authorities | Riparian London Boroughs (x14) Strategic planning: GLC (till 1986) | Riparian local authorities | Dept of the Environment |
| Note: nature protection sites include (SSSIs) and (AONBs); (NNRs), (LNRs). For the Greater Thames estuary area e.g. this included the SSSI at South Thames Estuary and Marshes (notified 1951, 1968). | Nature Conservancy Council (1973-91), responsible to Dept of the Environment | |||
| Sewerage | TWA District councils licensed as agents by TWA) | TWA ('main drainage', sewage treatment works, sewage disposal) London Boroughs licensed as agents by TWA | TWA; other RWAs District councils licensed as agents by RWAs | Dept of the Environment |
| Water Supply | TWA (plus private 'water only' companies under licence from TWA) | RWAs | Dept of the Environment National Water Council | |