The upper Wissey – and connected tributaries – is a small chalk stream flowing largely through agricultural and military land.
Rising to the east of the village of Bradenham, the river flows for 22 miles through the villages of North and South Pickenham, Great Cressingham, Bodney, Ickburgh before reaching Northwold. Watton Brook, Thompson Stream and West Tofts stream feed into the main channel.
The upper reaches of the river and Watton Brook tributary consist of a clay base. This means that they are more susceptible to “flashy” overland flows in the event of heavy rain. This underlying geology means that the impacts of anthropogenic modifications – such as canalisation of the channel – are more severe and that extreme flows, rather than being stored within wetlands in the upper reaches, are funnelled down the river leading to increased risk of flooding downstream.
Below the lower reaches lies an extensive chalk aquifer providing steady flows, consistent temperature and mineral rich waters, underpinning the unique ecology of the river.
Whist a majority of the upper Wissey has been classified by the Water Framework Directive as being of either moderate or poor ecological quality, it nevertheless has high conservation value and potential. Thompson Stream, left unmodified along some stretches, provides a tantalising glimpse of the true self-sustaining nature and potential of the river.