No evidence to suggest pollution from agricultural sources, but indicators to suggest it could be. Land use adjacent to the Fleet is mainly for dairy cattle grazing or arable rotations. Fleet hinterlands are mainly Oxford and Kimmeridge clays, cornbrash and Forest marble according to warden of Chesil and Fleet Nature Reserve). Fields have steep gradients leading down to the shores. Shoreline is colonised by gorse, blackthorn (Prunus spinosa), Hawthorn (Crataegus monogyna), bramble (Rubus fruticosa), Elder (Sambucus nigra) and many grasses. A few areas support saltmarsh vegetation. Land use varies along the Fleet from Ferry Bridge to the Tidmoor ranges (~5 km) are small fields for grazing of cattle and horses, some cut for hay, unchanged since the 19th century. Tidmoor ranges (MOD) are ungrazed and not managed for agriculture since the last century, the grassland being now encroached by gorse. From the ranges to Abbotsbury, the land is mainly used for intensive agriculture (arable and dairy). Non-intensively managed fields from Ferry Bridge to the western end of the Tidmoor ranges already have large areas between the fields and the edge of the lagoon. Intensively managed fields have been cultivated right to the margins of the Fleet. Dorset Heritage coastal footpath runs along the landward side of the Fleet.

No data on nutrient status of the Fleet, save NRA monitoring of tributaries. Reported pollution of tributaries of the Fleet, leading to loss of Ruppia and Zostera and occurrence of algal blooms, citing Elton, D 1991 (The Fleet and Chesil Beach Management Plan, Report to Ilchester Estate).

Mentions study by E.H. John, 1995 A study of the nutrient status, hydrographical features and phytoplankton composition of the Chesil Fleet, Dorset. University of Wales, Swansea (not in FSC archive). She suggests in this report that Athe nutrient levels of the Fleet waters do have a significant effect on the plankton population, and that nutrient enrichment in the Abbotsbury embayment supported the development of two algal blooms. She expresses concerns that eutrophication within the Fleet is damaging the lagoonal fauna.

Buffer strips for reduction of nutrient inputs from agricultural sources to the Fleet are recommended as a secondary conservation practice (after reduction of inputs at source). Their effectiveness will need to be monitored. Many fields along the Fleet have tiled field drains installed [report does not say which ones do], which will reduce the effectiveness of the buffer strips and lead to nutrient input direct to tributaries of the Fleet.

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