Dangerous waters

The water level here is a two or three metres higher than the water beyond which is known as the Relief Channel which is several miles long and meets the river Great Ouse on the outskirts of King's Lynn where there is another set of sluice gates.

The Relief Channel can accommodate excess water and avoid flooding - achieved by opening the sluice gates. The notice, enforced by the barrier of green drums prevents river traffic straying too close.