Freshwater - Drivers and pressures (Norway)
In the last 50 years, there have been major changes in settlement patterns and patterns of leisure activity in Norway. More and more people have moved from rural districts to urban areas, and major improvements have been needed in the way waste water from towns and urban areas is managed and treated. The changes in settlement patterns have put more pressure on watercourses near the largest urban areas. However, Norway utilises only one per mil of its water resources, and water extraction puts little pressure on water resources.
Environmental pressures on Norwegian rivers and lakes can be divided into three main groups:
•pollution: includes point sources, fugitive emissions, and long-range transboundary pollution, which may result in acidification, eutrophication and the spread of hazardous substances
•physical alteration: mainly as a result of hydropower developments, but other examples are transport infrastructure, which may act as a barrier to fish migration, and canalisation of rivers for agricultural purposes
•biological pressures: include the introduction of alien species such as minnows and pondweed, the escape of farmed fish, and parasites such as salmon lice.
The most important pressures on Norwegian water bodies are long-range pollution and morphological alterations of water bodies, followed by pollution from agriculture and waste water.
Major hydropower developments are not an issue at present, but existing plans and regulations pose great stress on habitats. Hydrological alterations in form of fluctuations, dry rivers and sedimentation impair quality on habitats and can have lethal effects on species.