River Whitewater

The River Whitewater rises from springs near Bidden Grange Farm in Hampshire, flowing northeast to join the River Blackwater. Its upper reaches pass through Odiham Fen, a Site of Special Scientific Interest where chalk springs feed clear, stable waters. Greywell Mill’s small building and attached house stand beside Mill Head pond, a grade II listed structure. The river then flows past Deptford Bridge and the eastern portal of Greywell Tunnel, built in 1792 for the Basingstoke Canal. Greywell Pumping Station extracts groundwater from the chalk aquifer, supplying drinking water since the early 1900s. Odiham Castle’s octagonal keep, possibly built for King John between 1207 and 1212, overlooks the river near the canal’s aqueduct. Warnborough Mill, dating from the 18th century, has been converted into a restaurant after serving as a milling site. Lodge Farm’s 15th-century timber-framed hall-house and the remains of a Roman villa lie along the banks further downstream. Poland Mill, with one remaining cast-iron water wheel, and Hook Mill, now part of a single house, show the river’s milling history. The river supports brown trout and coarse fish, though weirs block upstream movement and fragment habitats. Sections are managed as trout fisheries, with stock added from hatcheries to sustain populations. Dipley Mill’s deep, slow waters and shading Alder trees reduce plant growth, affecting trout food sources. Signal crayfish burrow into banks, worsening erosion where historic mill works have raised water levels. The Wild Trout Trust recommended removing some weirs and adding woody debris to improve flow and silt conditions. Water-crowfoot grows where gravel beds and faster flows return, supporting healthier ecosystems.