An "ecological disaster" is unfolding at one of Ireland's largest lagoons, according to experts, with algae blocking out light leading to plants and animals dying.
The Department of Heritage has said a number of actions are under way to address the pollution levels in at Lady's Island Lake in Co Wexford.
Experts are calling on the department to put together a multi-agency response to try to remedy the problem.
The 300 hectares have long been regarded as having great ecological significance. It is designated as both a Special Protection Area and a Special Area of Conservation.
Watch: 'I have never seen anything as bad as this' - expert
It is also a place of pilgrimage for many.
At first glance, all looks as it should be, but what is unfolding in these seemingly calm waters has been described as an "ecological disaster".
On closer inspection, pockets of algal are dotted all around, sitting on the water in between the reeds. There is also a smell.
"This lake, from many points of view, is dead," said Dr Brendan O'Connor, a marine biologist and co-author of a recent EPA report into the condition of the lagoon.
His analysis is stark.
"It's really, really bad. There are very few other examples of how bad it is in Ireland that I've seen and I've been looking for the last 40 to 45 years."
The cause, he says, is excessive nutrients in the water which give rise to the high production of algae, which grow at such a density that they block out the light and stop the plants that were growing on the lakebed.
"The animals that lived on the seabed are gone. The plants that lived on the lakebed are gone as well," Dr O'Connor said.
The EPA study indicated that agricultural run-off was the source of the excess nutrient levels. It measured at seven times what it should be.
"It's very, very clear that the cause of the collapse is due to excess input of nutrients from the surrounding land," said Dr O'Connor.
Ger Carty, a local councillor, grew up next to the lagoon and describes it as "one of the jewels in the crown" of tourism in the area.
He said the problem has been known about for years but "little or nothing" has been done about it.
"Lady's Island Lake is an area of significant ecological importance in Co Wexford, an area of fantastic natural beauty," he said.
"Unfortunately, we don't have a functioning ecological system here in the lake. There are issues in the context of nitrates but we need a joint venture between all the stakeholders - Wexford County Council, the EPA, the National Parks and Wildlife and the IFA.
"There's a part to play here with everyone the community... and this is not about a blame game."
In a statement, the Irish Farmers' Association said "no one is happy" with the situation in the lagoon.
"The reality is that everyone is continuously learning more and more about the optimal application of nutrients. Losing nutrients to water is a lose-lose and farmers would be committed to being part of a solution to address the issues that have arisen," it said.
The IFA also said it would support a multi-agency approach in trying to bring about a remedy.
Calls for such an approach have been increasing in recent times, including from Jim Hurley, a naturalist and a member of the local drainage committee.
He said the current state of the lagoon has been years in the making.
"The first time that a serious problem was identified was back in 1983 over 40 years ago, and at that time, the front page of our local paper described the lake as a cesspool," Mr Hurley said.
"The pollution is in the water so it doesn't have an immediate, direct effect on local people.
"Wexford County Council put up signs saying no swimming in the lake, for obvious reasons, and when we had significant algal blooms, signs went up advising dog owners not to let their dogs in the water, or not to let them drink the water.
"But apart from that, the main indirect impact would be the effect on the local economy, particularly with the summer tourism season about to start.
"Lady's Island Lake is a wonderful area and bad publicity about it is not welcome."
Mr Hurley is now backing a wider response saying the time to act it now.
"Lady's Island Lake supports the most diverse lagoon community in the country. It's worth conserving … the pollution needs to be ameliorated to bring back the wildlife community," he said.
In a statement, the Department of Housing, Local Government and Heritage said "a number of actions" are under way by relevant authorities to address the pressures at the lagoon.
It said assessments are being carried out to confirm the location of discharges and that will inform the "selection of measures that are likely to be effective in mitigating nitrate and phosphorus losses".
Any action to ameliorate the problem cannot come soon enough, Mr Hurley said.
"It's in a bad way. It's teetering on the brink, and now is the time for action to bring it back."
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