Vurdering av typologi og klassifisering av Hydros sjøvannsresipienter i Norge iht. Vannforskriften. Del 2- Høyangsfjorden

NIVA has on commission from Norsk Hydro ASA evaluated the characterization and classification, performed by the County Governor on the Norwegian Environment Agency website “Vann-Nett”, of the water bodies used by Hydro aluminum plants as recipients. The task was to verify that the procedures and data sets used in the classification and characterization were in accordance with the guidelines in the Water Framework Directive and the Guidance documents published to facilitate such a process. NIVA has been a major contributor in the process of developing new metrics for the Biological Quality Elements (BQE) and responsible for the scientific content and procedures in the guiding documents developed for evaluating status of our Water Bodies (WB). The status classification is defined by two systems – one ecological classification and one chemical classification. The chemical status is evaluated based on specific hazardous pollutants that are defined on EUs- list of prioritized hazardous pollutants and consists of 45 substances. Certain critical concentration levels – EQS-values (Ecological Quality Standards) are listed for each of the 45 substances in water as well as a few in biota (biological material). None EQS are listed for sediments. If a WB does not achieve compliance with all the EQS established in the annex 9 and 10 of the WFD i.e. exceed the EQS-values on EU-list, the status is set to fail to achieve good” status. If one fails to obtain good chemical status one has to implement action plans to improve water within a river basin management plan (RBM)(exemption can be made). Ecological classification is primarily based on Biological Quality Elements (BQE) and is classified according to its EQR (Ecological Quality Ratios) (indices) on a 5 step scale from Very Good to Very Bad. The EQR is a ratio between the observed value of the index, and the reference value for the index i.e. reference condition (= undisturbed condition). The BQE are phytoplankton, macro algae, angiosperms and invertebrates on soft bottom. All the indices developed in Norway are intercalibrated with other EUnations with the same water type (WT). Eutrophication, organic input and sedimentation are the stressors (pressures). Ecological status can be downgraded by the physio-chemical and hydromorphological quality elements and if the Quality Standards (concentration limits) of the river basin specific pollutants (RBSP) are exceeded...