The Jizera Mountains (North Bohemia, the Czech Republic) are located in the area of the “Black Triangle“, the epicentre of acid atmospheric deposition in Europe. Anthropogenic acidification strongly affected chemistry as well as biota of drinking water reservoirs Josefův Důl and Souš in the last century.
The contribution brings a qualitative and quantitative evaluation of long-term phytoplankton development in the two water dams (1993 –2012). The effect of anthropogenic acidification and recovery from acidification on the composition and biomass of the phytoplankton in two drinking water reservoirs on the upper plateau of the Jizera Mts.