The effects of a recent dumping of 16,000 m/3 of spoil in a licensed dumping ground within the Salcombe and Kingsbridge Estuary were studied during September 15th - 19th, 1987. The area was mapped using a combination of echo soundings and observations by divers. An area of earlier dumping activity was also included in the survey. The habitats and communities inside the area and on the surrounding sea bed were described and documented by diving biologists in September 1985, and results compared with those obtained during a survey carried out prior to the latest dumping programme. The main effect of the dredge spoil was to smother all life over approximately 23,000 m/2 of the sea bed. Outside this area of blanket cover there was increased siltation on the sea bed for at least 200 m to the north. Older clay from previous dumping operations was little different in appearance from the new clay and had only been colonised by a few species giving rise to a community very different from that of the natural sea bed. Sites well to the south around the Marine Hotel did not appear to be affected. The sea bed under the recent and earlier spoil dredgings, amounting in total to around 10% of the available habitat of mixed sediments, stones and shells is thus thought to be irreversibly changed by these operations and it is recommended that no further dumping of this type of spoil should be undertaken within the estuary. Records currently considered sensitive have been removed from this dataset.