BBC Northern Ireland rural affairs correspondent
Radical changes in farming practice are being proposed to help turn the tide of chemical pollution which is choking one of Europe's biggest lakes.
Restrictions on spreading animal manure and fertilisers are being planned in a move which would see Northern Ireland declared as a nitrates vulnerable zone.
Excess chemicals often end up feeding into rivers and lakes
The Republic of Ireland has already introduced stringent measures to tackle the problem.
More than 8,000 tonnes of nitrates pour into Lough Neagh in the centre of Northern Ireland every year, with the agriculture industry to blame for at least 75% of the pollution.
Chemicals from sewage works servicing some rural towns also contribute to the problem.
Every day, the rivers which drain some of Northern Ireland's most fertile farmland carry more pollution downstream.
The main problem is caused by slurry spreading and the use of fertiliser which contains large amounts of nitrogen.
Cattle and pig farms produce more than two billion litres of slurry annually.
A shortage of storage facilities mean that, all too often, the liquid manure is spread on waterlogged land at the wrong time of year.
Many soils cannot absorb the nutrients, and the excess chemicals are washed down through drains and streams which feed into rivers and lakes.
Across large swathes of Northern Ireland, grass and crops are blooming as fertiliser, farmyard manure, poultry litter and slurry are heaped onto the land.
The chemicals encourage weeds which starve the lough of oxygen
Lough Neagh though has gradually become like a chemical soup, with an ugly algal scum disfiguring its 125 kilometre shoreline.
But the damage is more than cosmetic.
Beneath its surface, fish are left gasping for oxygen. The nitrates and phosphates draining into the lake stimulate the growth of weeds, which in turn starve the water of oxygen.
The image abroad may be of sparkling lakes and rivers, but the Stormont Environment Minister, Angela Smith, says Northern Ireland has a serious water quality problem.
A survey of lowland lakes has revealed that 70% are polluted with chemicals, and the government accepts the situation is getting worse.
But turning the tide of pollution will have major implications for Northern Ireland farmers.
Agriculture Minister Ian Pearson says while farming plays a vital role in preserving and enhancing the environment, it is also a major source of environmental pollution.
"Because of the widespread nature of the problem, we are proposing to introduce mandatory measures to regulate farming activities throughout Northern Ireland," he said.
Restricting slurry spreading to dry weather during the growing season would mean that many farmers would have to invest in additional slurry storage.
Mr Pearson is hoping to gain EU approval to make grant aid available towards the cost of investments in new or improved farm waste storage and handling facilities, at a rate of 40% on the first £85,000 of eligible expenditure for each agricultural business.
The Ulster Farmers' Union says that would still leave farmers needing to find a lot of additional money to invest in new slurry stores and equipment.
The union is worried that some farms will be forced to make cuts in livestock numbers.
The UFU's deputy president, Campbell Tweed, says a closed period when slurry spreading is prohibited and maximum limits on the amount of organic nitrogen which can be spread per hectare, are key issues which will re-shape many farm businesses.
"The Ulster Farmers' Union will be working towards environmental regulations which protect the environment in a way which minimises the adverse effects on farming businesses and their incomes," he said.
The new anti-pollution measures are expected to come into force next year, but water quality experts say it may take a decade or more to reduce pollution levels, which have more than doubled in the past 30 years.