Barkham Brook is a small river in the English county of Berkshire. It has sources to the north and west of Finchampstead in the Wokingham Borough, flows past the village of Barkham, and joins the River Loddon to the west of Winnersh.
Route
Barkham Brook begins as a series of drains on The Moors, an area of woodland to the north of Finchampstead close to Sand Martins Golf Course. It is augmented by other drains before it passes under Nash Grove Lane, and heads in a westerly direction, where it is joined on its left bank by another stream, fed by a network of drains to the west of Finchampstead. As it approaches Barkham, it passes to the north of a moated site and enclosure. The irregular-shaped moat is between wide, and is around by in size. A raised field with ditch to the north-east of the moat is thought to be the farmyard of a manor, and the whole complex is a scheduled monument. Between the moated site and the brook is the grade II listed church of St. James, an Early English style building the nave of which was constructed in 1862 by John B. Clacy and Son, while the chancel and transepts were added 25 years later. It contains an effigy of a woman in a long flowing dress and linen headdress, made from oak in the 13th century. In Barkham, the brook flows under Barkham Street and is then joined by a tributary on its left bank, flowing northwards from California.
The tributary begins at Longmoor Lake, which covers and is situated in California Country Park. It was created by John Walter III, who extended an original pond after he bought the land to expand his Bearwood Estate in 1873. The clay which was excavated to construct the lake was used to make bricks. In the 1930s, the area became the California-in-England holiday camp, with attractions including a speedway track, but became a designated Country Park in 1980. The outflow from Longmoor Lake flows through Longmoor Bog, a Site of Special Scientific Interest (SSSI) covering , notable because it is one of the few base-poor valley mires in Berkshire. It includes an area of wet heathland, where peat sits on top of an underlying layer of clay, resulting in a ferruginous swamp, characterised by rust-coloured iron bacteria. Around the waterlogged mire are carrs of alder, grey willow, downy birch and alder buckthorn, while the swamp is populated by purple moor grass and cross-leaved heath.
At the western edge of Longmoor Bog, the brook is crossed by Park Lane, and turns to the north along the perimeter of the former Arborfield Garrison, which closed in 2015 to be re-developed for housing. After passing under Biggs Lane, it enters another lake, and then crosses open countryside to join the main channel, the combined flow continuing northwards until it is crossed by the B3349 Barkham Road. It is joined by a stream flowing westwards from the lakes at Barkham Manor. The grade II listed manor house was built on a moated site in the 17th century, and was enlarged in the 18th and 19th centuries, after which it was altered in the 20th century. It was the home of John Walter, and Mary Ball, the mother of George Washington, was born there. The brook continues to the north-west, and its flow is augmented by the treated effluent from Arborfield Sewage Treatment Works. The works is authorised to discharge 4.75 Ml per day into the river, but on 29 September 2013 discharged untreated effluent, resulting in serious pollution and the death of fish, other fauna and vegetation. Thames Water were fined £150,000 for that particular incident, as part of a much larger fine for five other incidents elsewhere.