| Thames Barrier | |
|---|---|
 View of the barrier gates, which are closed when a high tide is forecast | |
| Country | United Kingdom |
| Location | London |
| Coordinates | 51°29′49″N 0°2′12″E / 51.49694°N 0.03667°E |
| Purpose | Flood control |
| Status | Operational |
| Construction began | 1974 |
| Opening date | 8 May 1984 |
| Construction cost | £534 million |
| Built by | |
| Operator(s) | Environment Agency |
| Dam and spillways | |
| Type of dam | Barrage |
| Impounds | River Thames |
| Height (thalweg) | 20.1 metres |
| Length | 520 metres |
| Turbines | 0 |
| Website GOV.UK page | |
The Thames Barrier is a retractable barrier system built to protect the floodplain of most of Greater London from exceptionally high tides and storm surges moving up from the North Sea. It has been operational since 1982. When needed, it is closed (raised) during high tide; at low tide, it can be opened to restore the river's flow towards the sea. Built about 2 miles (3.2 kilometres) east of the Isle of Dogs, its northern bank is in Silvertown in the London Borough of Newham and its southern bank is in the New Charlton area of the Royal Borough of Greenwich.