It was a corn mill, but finished its working days grinding product for a mushroom farm, built nearby.

However, work to extend it began in 2009, and water from the upper Layer Brook is now pumped into the reservoir, because its level has been raised by 10.5 feet (3.2 m).

It is joined by a tributary flowing north-eastwards from Birch, and turns again to the east, passing under the B1026 Kings Ford Bridge to the north of Layer de la Haye.

[1] On the south bank is Roman River Valley, a 44-acre (18 ha) nature reserve, managed by the Essex Wildlife Trust.

This is one of the few remaining sites of unimproved acid grassland in Essex, and is notable as the habitat for over 1000 species of moths and butterflies.

This rises near Tiptree Heath, close to the 160-foot (50 m) contour, and passes under a minor road and the B1023 on the northern edge of Tolleshunt Knights.

[7] Water can no longer move from the west of the reconstructed causeway into the main reservoir by gravity, and a pumping station was constructed in its centre to achieve this.

[8] The reservoir is of international importance for wildlife, and is an SSSI, a designated Ramsar site in recognition of its wetland status, and a Special Protection Area in order to safeguard its habitats for migratory birds.

The mill burnt down in 1936, when the oil generators caught fire, but was rebuilt in corrugated iron sheeting, and became electrically powered.

[13] In 1997, a six-month project began to demolish the concrete silos and remove the asbestos, which revealed the mill building and a four-storey Victorian granary.

[16] The manor of Layer de la Haye had been given to Eustace, Earl of Boulogne, after the Norman conquest, and he had built a water mill.

[17] In 1536, the mill was one of a number of properties in the area seized by Sir Thomas Audeley, Lord Chancellor of England, in the wake of the dissolution of the monasteries.

The present building is of two storeys, with a timber frame, external weatherboarding, and a slate roof, which was Grade II listed in 1982.

They were small affairs, serving the needs of the local population, and both were fulling mills, involved in the processing of cloth, particularly wool.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.

Reasons for the ecological quality being less than good include runoff from agricultural land, discharges from sewage treatment works and the transport infrastructure, and surface water abstraction affecting the flow in the river.

Like most rivers in the UK, the chemical status changed from good to fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE), perfluorooctane sulphonate (PFOS) and mercury compounds, none of which had previously been included in the assessment.