This article reviews the influence of the Chernavodska nuclear power plant on the aquatic environment of the Danube River in the transboundary context. Data of tritium discharges, dependence of volume activity of tritium in the Danube River, and its inflows from the surrounding areas to its mouth. The average annual volume activities of tritium are provided. Assessments of the impact of the Chernavodska NPP in conditions that are different from the norm have been given.