Abstract <p>The article considers the most significant features of modeling the cycle of compounds of nutrients nitrogen and phosphorus and the dynamics of dissolved oxygen in the ecosystem of Lake Teletskoye. The model was calibrated taking into account the data of long-term observations of water quality in 1985–2003, as well as the scenario version of the hydrological regime of 2016. The intra-annual variations of state variables, external and internal fluxes of nitrogen and phosphorus compounds in the water of Lake Teletskoye were analyzed. A preliminary estimate of the permissible load of nitrogen and phosphorus on the lake was made. Model analysis showed that the assimilation potential of the lake with respect to phosphorus compounds is insignificant, practically absent. In relation to nitrogen compounds, a small potential of self-purification is still available. The water of Lake Teletskoye is clean due to the still low anthropogenic load. The obtained model results indicate an urgent need to bring research on Lake Teletskoye to a modern level both in terms of the number of observation points of the monitoring network in characteristic zones, an increase in the list of monitored indicators and the frequency of control, and in improving the quality of the instrumental and methodological base.</p>