The Letcombe Brook, in common with all chalk streams, faces a number of serious threats, including physical modification, over-abstraction of water, pollution from sewage works, septic tanks and agriculture, climate change, population growth and expanding populations of non-native species, such as American crayfish, mink, Himalayan balsam and Japanese Knotweed. A 2014 report published by the World Wildlife Fund stated that England’s chalk streams were ‘in a shocking state of health’ and emphasised the need for urgent action to protect them. Letcombe Brook currently fails the criteria set by the Water Framework Directive and work is needed to improve the health of this precious chalk stream.

The Letcombe Brook faces particular pressure at the moment from the amount of development being carried out in the catchment area. Strategic Housing Allocations have identified over 9,000 new homes to be built in the local area up to 2031. The Letcombe Brook and its environment is at particular risk from greater levels of pollution caused by homes, businesses and agricultural practices and the increased pressure placed on this precious resource by new developments. Even more sewage will have to be processed by the Wantage Sewage Treatment Works which discharges to the Letcombe Brook north of Grove.