For centuries oystermen have scooped their harvest from the Carrick Roads estuary in Cornwall.
Motors have always been banned and until now the fishermen's greatest asset has been the purity of the water. But now that is threatened by sewage.
South West Water has spent pounds 10m on a treatment works and a deep-water outfall at Black Rock -in the middle of the entrance to the Carrick Roads estuary.
And to the oystermen's horror, sewage from the plant is to be pumped just 450 metres away from the beds, after no more treatment than sieving. Now a legal battle is brewing over the outfall.
Alun Davies, chairman of the Port of Truro Oyster Dredgermen Association, who has worked the beds for 26 years, said: "Our concern revolves around the tidal flows. At the moment, the sewage pumping is timed so that it is pumped out on an ebbing tide, so the tidal flows will do South West Water's dirty work for them and carry the sewage out to sea. "Our fear is that if we have a strong wind, it is not going to be swept away. It will return on the next tide and go on to the oyster fishery.
"The water company has shown us computer predictions saying this can't possibly happen, but that's ridiculous. It's difficult to believe the mentality that says the sea doesn't do unpredictable things. In this day and age, to pump sewage out after just sieving is criminal."
Deterioration of water quality would quickly close the Falmouth oyster fishery. At the moment the area around the beds is "B-rated'',meaning the oysters require 48 hours of ultra-violet treatment before they are safe to eat.
But if the water quality declined to "C", the oysters would have to be relaid in "A" standard water for two months before reaching the marketplace. "It's such a performance the fishery would simply close overnight," said Mr Davies.
The Falmouth oyster fishery was almost destroyed by a viral infection in the 1980s, but since then there has been a slow recovery. Now 80 men work there. "It makes it all the more galling, to have beaten off the threat from nature, only to face an even greater threat from South West Water and the Environment Agency," said Mr Davies.
"Our oysterbeds should be a model of a sustainable fishery. Instead they are threatened by the people who are meant to look after these things."
However, South West Water defended the move, saying: "We are confident that objective assessment will confirm the scheme is operating in accordance with the consent set by the Environment Agency, the water industry's environmental regulator. Previously, crude sewage was being discharged continuously into the estuary.
"On occasions, beaches have been closed as a result of sewage pollution. By the year 2000 we will add two stages of treatment to the new system to comply with the Urban Waste Water Treatment Directive."
But the oyster fishermen are demanding ultra-violet and nitrate stripping treatment on discharges from the plant. Armed with statistics showing bacteria levels 50 times higher than EU safety standards for bathing waters, the area's port health authority is seeking legal advice before applying for an abatement order against the water authority.
If the port health authority wins its case, the sewage pumps will have to be switched off. But Mr Davies says he is sad such action should be necessary.
"It's not just the oysterbeds," he said. "We have sailing competitions during the summer, yet we are pumping raw sewage into the middle of it. It is utter madness."Reuse content