Oysters have been harvested from the estuary for more than a thousand years and there are remains of Anglo-Saxon era fish traps. At the head of the estuary is the town of Maldon, which is a centre of salt production. The other major settlement is the town West Mersea, of Mersea Island, on the northern seaward side. Numerous other villages are on its banks.
Within the estuary is Northey Island which was the location for the first experiments in the UK in 'managed retreat', i.e. creating saltmarsh by setting sea walls back from what are perceived to be unsustainable positions.
Almost 4.4 square kilometres (1.7 sq mi) of the Blackwater Estuary is a designated as Special Protection Area for wildlife. The area being notable as a breeding area for Little Tern Sternula albifrons and as a transit point for Ringed Plover Charadrius hiaticula.
- Over-wintering species
- Pied Avocet Recurvirostra avosetta;
- Black-tailed Godwit Limosa limosa islandica;
- Dark-bellied Brent Goose Branta bernicla bernicla;
- Dunlin Calidris alpina alpina
- Eurasian Golden Plover Pluvialis apricaria;
- Grey Plover Pluvialis squatarola;
- Hen Harrier Circus cyaneus;
- Common Redshank Tringa totanus;
- Ringed Plover Charadrius hiaticula;
- Ruff Philomachus pugnax;
- Common Shelduck Tadorna tadorna