A mass protest saw more than 200 people calling for an end to continued dumping of dredged material from the River Tamar in Whitsand Bay.
Campaigners say thousands of tonnes of “toxic silt” have been dumped off Rame Head, polluting Whitsand Bay, which is part of a recently established marine conservation zone.
Contractors, working on behalf of the Ministry of Defence, have dumped dredged material from Devonport Royal Naval Base and surrounding locations, at the site for years.
A fresh application for another two-year licence to keep dredging and dumping was lodged last month.
A decision is due to be made in early 2014 but opponents have identified an alternative site they say is safer and where the landscape is silt, a mile offshore.
Organiser Deb Hoskin said she was delighted so many had turned out in spite of the weather.
She said that people who had lived in the area since the 1960s and regularly used Whitsand Bay for swimming, fishing and diving had witnessed the “devastation” of the area over the past ten years.
“We just want it to stop,” she said. “It needs to be dumped somewhere safer.”
Edwina Hannaford, West Looe councillor on Cornwall Council, said she was concerned that the impact on the new Looe Bay Marine Conservation Area had not been understood.
Phil Hutty the Liberal Democrat prospective parliamentary candidate for South East Cornwall, said: “The inertia is created by people saying, ‘It’s not my problem’, when it’s everyone’s problem.
“Move the dumping offshore and leave this lovely bay alone.”
Local campaigner Claire Wallerstein said: “Around 6million tonnes have been dumped in this small bay, even though the Environment Agency said in 2005 that it had reached capacity.
“It will be a travesty if the new licence is granted.”
“Many locals and visiting tourists feel and act with a responsibility to the environment, from swimmers, to walkers, to fishermen and divers, caring by keeping the beaches and seas clean themselves; beach cleans have been happening regularly in all weathers.
“At the same time, this horrendous dumping is taking place, devastating much of the sea life. It has to stop.”
The last dredging at Devonport Dockyard in the Tamar took place on March 22 last year and the new application predicts that 367,000 tonnes will be extracted over the two-year licence period.
The application, by Boskalis Westminster Ltd, also admits the proposed disposal site falls within a conservation area.
The Marine Management Organisation said last month it expects to make a decision by early 2014, following a 28-day public consultation period which ended last month.
South East Cornwall MP Sheryll Murray and some of her constituents, along with Camborne MP George Eustice, a Minister at the Department for Food and Rural Affairs, also staged a meeting to discuss the issue of Rame dumping.
The cross-party delegation, organised by Mrs Murray included Independent, Conservative and Liberal Democrat councillors as well as residents.
After the meeting Mrs Murray said: “The dredging is vital to maintain the dockyards at Plymouth upon which so many constituents’ jobs rely.
“What I want to see is a different site used for the dumping. I would like to thank the local people who got together to identify a disused sewage site, which is a little further out, in much deeper water. This would let this material disperse more naturally.
"I would really like to thank the Minister for taking the time to come to South East Cornwall to meet local people to ensure that he is fully briefed before he meets with officials from the Department about this important local issue.
"I would also like to thank all the local people, and those from further afield who I urge to contact their own MPs, for the highlighting of this important issue today at the protest on the beach.
"Unfortunately my local advice surgeries stopped me from joining them but I certainly agree with their objectives and am working towards ensuring that the dumping at Whitsand Bay stops."