Permissible phosphorus and nitrogen loadings were calculated for 17 international (transboundary) water bodies, which allow them to remain in an oligotrophic state. The calculations were performed by the methods suggested by Vollenweider, Vollenweider and Dillon, and Lozovik. The study was based on mathematical models linking the permissible nutrient loadings on water bodies with their morphometric, hydrological, and assimilation characteristics. A statistically significant relationship was established between the permissible nutrient loadings on sixteen transboundary lakes and one transboundary storage reservoir and their catchment areas. The revealed quantitative ratios enable environment agencies to make informed decisions about the need for reducing human pressure on the investigated water bodies.