Vansjø-Hobøl Catchment, Norway

Vansjo Location MapREFRESH Catchment case studies - responding to future change: Vansjø-Hobøl Catchment, Norway 

The Morsa Catchment (right) extends across 690 km2 and includes eight municipalities. The Vansjø Lake, the basin’s main water body, provides drinking water for more than 60 000 people in and around Moss, the largest town in the area. The lake is an important outdoor recreational area for the region and is considered of national value to Norway. The sub-catchments studied in REFRESH are the Hobøl River, the western part of Lake Vansjø and the Skuterud Creek. Cost Effectivness Analyses (CEA) have been carried out for the Hobøl River and the Skuterud Creek.

The Morsa catchment was a pilot catchment for the implementation of the EU Water Framework Directive in Norway. Consequently, there have been numerous stakeholder activities, including workshops, interviews, seminars, and conferences. Therefore 'stakeholder fatigue' was a concern here. Discussions with local and regional management officials agreed to keep workshops to a minimum, and ensure that the issues discussed were of real significance for the stakeholders.

Analysis in this case study has focused on reduction of total phosphorus to reduce eutrophication problems. Key results from this are summarised as follows:

  • The most cost-effective combination of measures to tackle phosphorous pollution included (ranked in order of cost-effectiveness); Buffer zones; Sedimentation ponds; Reduced tilling ; Sewage from scattered dwellings; Transfer of sewage to Municipal Sewage Treatment Plants (MSTPs) outside the catchment.

  • However, because other concerns were also considered important (e.g. bioavailability of phosphorus, risks of bacteria from sewage pollution, as well as wider benefits) policy-makers and managers decided to implement the more expensive sewage measures as well.

  • There is considerable uncertainty with the cost-effect figures of measures to tackle diffuse runoff from agriculture. It may also take several years before the effect of such measures is visible in the river waters.

  • The disproportionality analysis showed that the reduction of phosphorus was proportionate and economically justified, but distributional effects and affordability considerations should be taken into account. The costs and benefits might not be borne by the same people, creating a ‘mismatch’ for incentivising the measures for water quality improvement. Payment for ecosystem services, where beneficiaries contribute as well as polluters, may therefore be considered.

  • The measures implemented in Vansjø-Hobøl have had wider benefits than the removal of phosphorus, and such benefits should also be highlighted to increase the motivation for stakeholders to carry out the measures.

  • The active engagement of stakeholders throughout the whole WFD planning process is considered as a key factor to ensure the design of economically efficient and socially acceptable water-quality improvement action.

    Key points

  • The effects of agricultural measures are not clear – these have been in place for over a decade yet there is no clear downward trend of phosphorus in the main river. Are we seeing a lag in response or are measures not being targeted appropriately?

  • The lake is still at risk despite huge investments in measures. Therefore motivation to continue the measures needs to be maintained.

  • Cost-effectiveness is not always considered as a priority. Sewage Treatment plants were prioritised, although these measures were not recommended by scientists. This was a political decision.

 Vansjo Catchment 1  Vansjo Eutrophication

Agriculture in the Vansjø-Hobøl catchment Photo: E. Skarbøvik

Eutrophication problems in lake Vansjø Photo: E. Skarbøvik

For further information see REFRESH reports

Workshop proceedings on collaborative scoping of solutions, Vansjø-Høbol catchment, Norway 

Cost-effectiveness Analysis reports for the Vansjø-Høbol catchment, Norway, including analysis of proportionality/disproportionality

Vansjø/Høbol modelling: final report