Eutrophication

In Norway the eutrophication of freshwater tends to occur in low-lying areas, particularly near settlements and agricultural land. Nutrient surpluses originating in Norway affect coastal areas such as fjords and skerries, whilst offshore the whole Skagerrak region is affected by emissions that originate far beyond Norwegian territorial limits. The results are depletion of oxygen in the fjords of Southern Norway and deteriorating living conditions for many organisms.

Inputs of nitrogen via acid rain further aggravates the nutrient surplus in Norway.

Modest inputs of nutrients may have a positive effect on biodiversity as well as the total production of the ecosystem. But too much will cause the ecosystem to accumulate excessive biomass.

Algae blooms, reduced light penetration and fouling

Possible results are massive algae blooms, reduced light penetration and fouling. Reduced light penetration in the water affects the distribution of attached algae and other water plants. Blooms of toxic blue-green algae severely restrict the use of the water. Decomposition of organic matter, either from increased biological production or inputs from human activities, will deplete the oxygen in the lake, especially in deep, still waters where little circulation occurs. Many organisms can suffer degradation of their habitat as a result.

In extreme situations fish may die

Once oxygen levels are low, phosphates and other salts will leak out of the bottom sediments, reinforcing the eutrophication process. In extreme situations, the water will contain toxic hydrogen sulphide gas, causing fish to die and bottom areas to rot.

Nutrient run-offs may cause disease

Nutrient run-offs from agriculture and municipal drains often cause hygenic problems, as such sources normally contain fresh excrement from livestock or man. Contamination with intestinal bacteria can carry a disease risk from pathological bacteria, virus or parasites.

The major changes in Norwegian society over the past 50-100 years and the economic development of the recent decades explain much of the increase in nutrients in circulation. More people now live in towns and urban settlements where wastewater quickly reaches recipients.

Agricultural production has intensified, and with it the reliance on artificial fertilisers. It is no longer necessary to make use of the naturally occurring nutrients, as it was a hundred years ago. More traffic and more industry also mean more emissions of nitrogen oxides to the atmosphere, which eventually reach the water system through precipitation or particles.

The expansion of the fish farming industry has resulted in large increases in discharges of nutrients over the past 20 years. The fish farming industry is now the largest source of human discharges of nutrients in Norway.

The major Norwegian sources of nutrients and organic materials are fish farms, agriculture, municipal waste-water and industry. Discharges to the Norwegian coast have increased from 1985 to 2006, due to the growth of the fish farming industry.

Along the coast from the Swedish border to Lindesnes at the southern tip of Norway, which is defined as Norway's problem area, discharges of phosphorus were reduced by about 60 per cent from 1985 to 2006. During the same period discharges of nitrogen were reduced by about 40 per cent. Agriculture and municipal waste-water are the main sources of discharges of nutrients along the Skagerrak coast. There is no fish farming industry in the area.

Agriculture- major source along the Skagerrak coast

Pollution from agriculture can occur directly by leakages or spills from manure and silage storage and from livestock and pasture land. Erosion of fertilised fields causes high levels of phosphorus to reach rivers with the displaced soil. Direct leakage from the soil is the most important source of phosphorus and nitrogen contamination to the Skagerrak coast.

Fish farms - largest source

Discharges from fish farms is the largest source of discharges of nutrients in Norway. Most Norwegian aquaculture takes place in net cages in the sea. Much good work has been done on feed qualities and feeding routines in recent years to correct the situation and the discharges per kilo fish produced have dropped. Yet Norway's total production of farmed fish has increased so much that overall discharges have increased over the past 15 years. Along the coast, from Lindesnes in the South to the Russian border in the North, discharges from fish farms exceed discharges from agriculture and the municipal sewer systems.

Discharges from households and industry

Municipal sewer systems generally serve urban areas where the waste-water from households and industry is collected and transported to a waste water treatment plant before being discharged. In less densely populated areas, such as in Norway's many mountain and seaside cabin resorts, there are often just septic tanks or basic separate treatment facilities, and in some cases unhygienic conditions may occur at the outlet. Industries are generally connected to the municipal sewers or have their own treatment plants.

Natural run-off is another major source of nutrients

General background run-off due to precipitation and natural processes in the soil and rock are another major source of nutrients in Norway. Traditionally contributions from the atmosphere have been thought of as part of this background. But in fact much of this originates from human activities, and deposits of nitrogen in particular are brought to Norway by long-range transport of air pollution. Coastal traffic, road traffic and industry in continental Europe are important sources.

Long-range pollution affects the coast

Deposits from the atmosphere largely come from continental Europe. The water masses along the North Sea coasts are enriched by nutrients and organic material from the major continental river systems. Surveys show that the Norwegian coast, especially from the Swedish border and west to Lindesnes, is periodically affected by long-range pollution from continental sources.

During the last 20 to 30 years, a number of measures have been carried out to reduce the discharges from agriculture, municipal waste water and industry. Similar measures have been carried out in large parts of Europe, beneficial to Norwegian waterbodies. Nevertheless, today’s discharges from the above sectors and fish farms are of significance for the water quality.

The strategy of the Climate and Pollution Agency is to:

• carry out further measures to reduce discharges to water bodies on the Skagerrak coast, and along parts of the south-western coast as well as other water bodies that have been eutrophicated or are at risk of eutrophication. Relevant means include stricter control on the purifying requirements in the pollution regulation and in the discharge permits, and to include purifying requirements in the competent authorities’ management plans.
   
• obtain further knowledge with regards to water bodies where increases in discharges are occurring but where environmental conditions are unknown. Relevant means include the use of § 51 under the Norwegian Pollution Control Act to impose environmental surveys on operations responsible for large discharges.
   
• influence neighbouring countries to further reduce their discharges through international co operation within Europe (EU, the OSPAR Convention and the integrated management plan for the North Sea).