Overvåking og problemkartlegging i Vannområde Valdres 2014

In 2014, Water District Valdres requested a status classification according to the Water Framework Directive (WFD) of 41 localities distributed among 16 lakes and 25 river sites. The biological quality elements assessed were phytoplankton in lakes and benthic algae and heterotrophic growth in rivers and streams. The chemical parameters phosphorus and nitrogen was also examined, and in selected locations near the freshwater pearl mussel areas in Begna, nickel, lead, zinc, copper, iron and aluminium were also analysed. Most localities achieved the environmental objectives set in the WFD; good or very good ecological status. The exceptions were the lakes Nordre Syndin and Reinsennvatnet along with the rivers Yddeåne and Øystre Slidreåne at Fossen camping. These localities all showed moderate status. For the two river stations, the acidification index was the decisive index and we found no signs of eutrophication issues here. In Reinsennvatnet there was good conformity between the biological and chemical results, both showing moderate status. In Nordre Syndin, on the other hand, the low status class was due to high phosphorus concentrations while the biological results were good (low chl-a). In this case it is worth mentioning that the location of Nordre Syndin is borderline mountain or forest with regards to altitude classification, and that if the lake had been classified as forest it would have been classified to good ecological status. Based on analyses of nutrients and eutrophication, the fish farms in Valdres do not seem to affect the benthic algae communities negatively, and measured concentrations are not harmful for the freshwater pearl mussel in Begna. However, the mean phosphorus concentration was high in the lakes from Beito-Øyangen to Hovsfjorden in 2014 compared with previous years. Although this did not lead to an increase in chlorophyll-a concentrations, these lakes should be monitored to determine the cause of the increase and whether the levels remain high. The measured concentrations of lead and nickel were very low resulting in good chemical status. Concentrations of copper and zinc were in the categories "moderately polluted" or "negligible polluted" according to the old national classes, which is slightly higher than the median value for Norwegian lakes, but probably not high enough to damage freshwater pearl mussels or other aquatic life. The concentrations of iron and aluminium were below the levels that produce toxic effects.