Vil endret vannføringsregime i Kvina påvirke saltholdighet og fare for remobilisering av giftig aluminium i Fedafjorden?

Sira-Kvina Kraftselskap is planning to transfer water from two sub-catchments (51.5 km2) in the uppermost part of River Kvina, to the neighboring River Sira. By increasing and distributing residual water flow better over the year, while at the same time carry out habitat measures, the intention is to maintain good conditions for Atlantic salmon despite the reduction in annual flow. Changes in the water flow regime in River Kvina can, however, affect the propagation and mixing of freshwater in the Feda fjord. It has been shown previously that aluminum from the river can be toxic to fish in the mixing zone between fresh water and brackish water, in particular when the salinity is in the range of 1-7 PSU. Continuous monitoring of temperature and salinity in the period 15 April - 17 September, as well as measurements of vertical salinity profiles 4 times spread over the same period, showed that a variation in water flow in Kvina of 20-60 m3/s gives a variation in the prevalence of the potentially toxic brackish layer (