case study: Morsa

1. Name Partner

Norwegian Institute for Water Research (NIVA), University of Life Sciences (UMB)

2. General case study characteristics

2a. Geographical characteristics

The Morsa catchment is an approximately 700 km² area in south-eastern Norway, including outskirts of Oslo in the north, a number of smaller lakes draining to the Hobøl river which runs into Storefjorden and Vannemfjorden in the south, which the drains to the Oslofjord through the city of Moss.

2b. Land use characteristics

Mainly forest and agriculture with the main urban area being Moss city (dark brown areas) in the southern end of the catchment.

3. Pressure and impact analysis

3a. Main pressure(s) and/or pollutant(s)

Vannemfjorden is a highly eutrophic lake with frequent cyanobacteria blooms in May-June. Total P loading in 2000 approximately 17 000 kg TotP. Main sources of nurient loading are agriculture(57%), septic tanks from individual households (11%), municipal wastewater (6%) and natural background run-off (26%). Nitrogen loading relevant to marine areas in Oslofjord in the context of complying with the North Sea Treaty. Little industry of significance. Other water quality issues are marginal compared to nutrient loading issue. Relative P-loading contribution by sector by sub-catchment. Source apportionment has identified near-shore irrigated vegetable agriculture as probable main contributor to surplus P.

3b. Impact(s)

Most of watershed currently at risk of not meeting ”good status” under WFD. Storefjorden provides drinking water supply for 60 000 people through the MOVAR water supply facility. Due to algal blooms and heavy turbidity in spring floods MOVAR recently invested approximately 10 million Euro in upgraded water treatment (flushing, ozone treatment).Storefjorden and Vannemfjorden serve as the aquatic recreational area for at least 33 000 people living locally. North Sea Treaty obligations in Oslofjord. See Figure 3 for overview of water use conflicts.

4. Definition goods and services provided by aquatic ecosystem

Nutrient run-off sink for upstream agriculture and households not connected to municipal sewage treatment. Aquatic recreation (swimming, sports fishing, boating).

5. Beneficiaries / stakeholders involved

Households (drinking water, recreation), agriculture (irrigation, run-off sink)

6. Definition environmental and resource costs and benefits

Welfare loss of aquatic recreationers due to bathing advisories during algal blooms (summer). Basic measures: Mitigation costs of downstream MOVAR water supply plant. Nutrient mitigation costs in agriculture (i.a. yield loss, buffer strips, sedimentation dams, grassy water courses), households (septic tank upgrades, connection to municipal treatment). Incremental management costs of the Morsa catchment authority. Incremental cost of supplementary measures to achieve GES in 2015.

7. Main objective monetary valuation environmental and resource costs and benefits

Demonstrate temporal transferability with 1995 contingent valuation survey. Demonstrate transferability of welfare estimates for mitigating eutrophication impacts on recreation and water supply to other eutrophied catchments in Norway, in the context of assessments of disproportionate costs of programme of supplementary mitigation measures under WFD.

8. Economic valuation method

Contingent valuation of recreational benefits. Mitigation cost accounting.

9. Key methodological issues

Linking economic values to pressure and/or biological impact indicators using e.g. Bayesian networks
Aggregation of household welfare estimates to accurate definition of recreational user population in the context of many substitute aquatic recreation sites.
Benefits transfer across sub-basins, taking into account spatial (upstream-downstream) interrelationships and possible substitution effects (recreation). Temporal and spatial transferability.
Possibility of creating a GIS based value map

10. Available data, information sources and stakeholder involvement

Article 5 report (pilot study 2003) (Hovik, Selvik et al. 2003, Lyche Solheim et al. 2003)
Cost-effectiveness analysis of Tot P mitigation measures (Lyche Solheim et al. 2001)
Contingent Valuation survey and benefit transfer study carried out in 1995 in Morsa and neighbouring catchment (Magnussen, Bergland, Navrud 1995)
Long time series water quality monitoring data. Dynamic nutrient transport and lake eutrophication models calibrated and verified
Decision analysis of Tot P mitigation measures (cost-effectiveness and cost-benefit analysis) using Bayesian network software (Barton et al. 2006)
Environmental impact analysis of supplementary measures under WFD.

Case Study Status Report Morsa, May 2007 [pdf, 2.5 MB]