Chlorophyll Content and the Modern Trophic State of the Volga River Reservoirs (2019-2020)

New data on the chlorophyll a (Chl a) content, determined by the standard spectrophotometric method in the Volga River reservoirs in summer 2019 and 2020, are presented. Chl a content was typical of the phytoplankton summer maximum and varied from 100 mu g/L. As in previous years, a local increase in Chl a was observed in near-dam areas, in littoral waters, and in tributaries and their mouths. The maximum increase was recorded in the Shosha Reach of the Ivankovo Reservoir and in the mouth of the Oka River in the Cheboksary Reservoir. The average Chl a concentrations during the observation period characterize Ivankovo, Uglich, and Cheboksary reservoirs as eutrophic and Rybinsk, Saratov, and Volgograd reservoirs as mesotrophic; the trophic status of the Gorky and Kuibyshev reservoirs varied from mesotrophic to moderate eutrophic.