According to field observations during 1995–2005 and 2012–2016, the pigment composition of phytoplankton in the Upper Volga reservoirs is given. With an average Chl a content of 13,1±1,4 to 52,5±2,7 μg/L in the Ivankovo reservoir and from 4,1±0,9 to 27,5±2,5 μg/L in the Uglich reservoir, an increase in Chl a was noted after an abnormally hot 2010. The content of Chl a in the Ivankovo reservoir retaining eutrophic status does not go beyond the limits of long-term fluctuations. In the Uglich reservoir, an increase in the absolute and relative amount of Chl a was revealed, indicating the transition of the reservoir to the eutrophic category.