Deliverable 6.15

Abstract: Cost-effectiveness Analysis report for the Vansjø-Hobøl catchment, Norway, including analysis of proportionality/disproportionality

In this study, an analysis of cost-effect (CEA) and disproportionality (DA) of measures to combat eutrophication in the Norwegian case study, Morsa (Vansjø- Hobøl), has been carried out. The analysis is based on a combination of results from a wide range of former studies, interactions with stakeholders through interviews and workshops, as well as some inputs from WP5. The analysis has focused on reduction of total phosphorus to reduce eutrophication problems and the most cost-effective combination of measures included (ranked in order, with the most cost-effective measure first and the least last):

  1. Buffer zones with vegetation along creeks and rivers
  2. Sedimentation ponds
  3. Reduced tillage practices (leaving the fields in stubble during winter)
  4. Reduce sewage from scattered dwellings (stand-alone systems)
  5. Transfer of sewage to municipal sewage treatment works outside the catchment.

Caution needs to be taken when using these results in practice. Managers should for example not only consider the cost-effect of removal of total phosphorus, but should also consider other concerns, such as the bioavailability of phosphorus from different sources, and risks of bacteria from sewage pollution. Amongst others for this reason, the most cost-effective measure was carried through in this catchment. It must also be stressed that the cost-effect figures for measures to tackle diffuse runoff from agriculture are uncertain, and it may take several years before the effect of such measures is visible in the river waters.

Through stakeholder interactions this analysis also identified a large range of wider benefits from these measures, ranging from improved cooperation across administrative borders to increased well-being of the local population. It is believed that such benefits may contribute to the continued motivation for implementing measures.

The disproportionality analysis showed that the reduction of phosphorus in the case study catchment was proportionate and economically justified, but distributional effects and affordability considerations should be taken into account. Payment for ecosystem services, where beneficiaries contribute as well as polluters, may therefore be considered. The active engagement of stakeholders throughout the whole WFDplanning process has been considered as a key factor to ensure the design of economically efficient and socially acceptable water-quality improvement action in this catchment.

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