Dungeness in Kent is the largest shingle system in the British Isles, and comprises five distinct beaches. Denge Beach is the largest of these beaches and contains a series of open water bodies, which support a diversity of fauna and flora. Gravel extraction and water abstraction for public supply has been present in the Denge area since the end of the 19th century. A deterioration of a number of patches of blackthorn (Prunus spinosa) scrub and important epiphyte species found on the blackthorns was observed during the early 1990s. This paper examines the nature of the shingle aquifer, water-level fluctuations, the influence of human activity, and their relationship with the deterioration of blackthorn and epiphyte communities. It is found that water levels have steadily risen since the early 1990s and the deterioration of blackthorn scrub was probably related to high chloride levels caused by ingress of seawater.