Monitoring Vansjø-Hobølvassdraget
Together with NIBIO, we carry out operational monitoring of rivers and lakes in the Morsa water area (Vansjø-Hobølvassdraget).
- Project period
- -
- Funders
- Vannområdeutvalget Morsa
- Total budget (NOK)
- 400,000
- Research section
- Freshwater Ecology
- Contact person
-
Sigrid Haande
- Involved from NIVA
-
Birger Skjelbred
About the project
The Vansjø-Hobøl watercourse is a nutrient-rich lowland watercourse that stretches from Østmarka in Oslo and Akershus to Vansjø and Moss in Østfold. The catchment area is 688 square kilometres and large parts of the catchment area is below the marine limit, i.e. the highest level that the sea reached during the post-glacial period following the last ice age. Large parts of the catchment area are covered by forest. Agriculture is practised on about 15% of the area. There are around 40,000 inhabitants in the catchment area, spread across large and small towns and scattered settlements. There are also a good number of cabins in the catchment area. The official name of the entire catchment area is Vansjø-Hobølvassdraget – or Morsa, as it was originally known. In addition to the Vansjø-Hobølvassdraget, the Morsa River Basin District includes the coastal areas west and south of Lake Vansjø.
The Vansjø-Hobøl watercourse is heavily influenced by agricultural runoff, dispersed drainage, and erosion, and there are major problems with eutrophication in rivers, streams, and lakes in the catchment area. There has been a particular focus on Lake Vansjø, where for many years there was a severe bloom of cyanobacteria (also called blue-green algae). As a consequence there was at times a recommended ban on swimming in parts of the lake. Several mitigating measures have been implemented in the catchment area, including changes to soil cultivation and reduced fertilisation (including binding agreements between farmers and the county governor), cleaning up dispersed drains, establishing buffer zones along the watercourse and building catchment ponds.
A detailed description of the Vansjø-Hobøl watercourse is given in Skarbøvik and Bechmann (2010). The water area has been one of two Norwegian pilot areas for testing the Water Framework Directive in Norway and extensive annual monitoring of rivers, streams, and lakes in the watercourse is carried out. NIVA is responsible for monitoring selected lakes in the water area.