Data on changes in the qualitative composition of volatile organic compounds and content of elements in waters of the Bureiskoe Reservoir after a great landslide, which blocked access to the hydroelectric power station, were presented. Blasting with use of trinitrotoluene and hexogen carried out to restore the hydrological regime by creating an artificial channel. Maximum content of methanol and acetone were recorded in water samples taken at the right bank near the landslide, where a lot of disintegrated wood entered the water after river tsunami. After filtering water through a landslide body, the content of Al, Fe, and Pb increased, and content of Mg, Ca, Zn, and Cd decreased. After restoration of the reservoir flow in water samples from the artificial channel, the content of Fe, Mn, Al, Cu, and Zn was at a low level and did not reach the initial values established before the blasting began. However, an increase the content of Pb by 7 times and Hg by 80 times was recorded. Presence of methanol and methylated benzene derivatives in water could stimulate the formation of more toxic bioavailable methylmercury, posing risks to aquatic organisms.