During the second half of the 20^th century the large European lakes: Ladoga and Onego were under the influence of anthropogenic factors and climatic changes. Trophic status of these lakes also changed. It is rather difficult to estimate separately how climatic and anthropogenic factors impact on lakes ecosystems and especially to predict future development. The economical collapse in Russia in the 1990s led to a decrease of the phosphorous loading and water quality of these lakes improved. An increase of economic activity in 1998-2008 has resulted in a higher nutrient load in Lake Ladoga and Onego that, in turn, initiated the observed deterioration in water quality. The forecast of  the maximum permissible load is complicated by effects of regional climate warming, which should be taken into consideration as well. The climate variations may strengthen or weaken the anthropogenic nutrient load affect to these lake water ecosystems.