The article presents some results of researching the stability of selective estimations of statistical parameters for various time intervals of numbers of the maximum charges of spring high water in the basic rivers of Belarus for the period of tool supervision. Pieces of lines with a varying degree of anthropogenous influence on a drain and with different types of atmospheric circulation are considered. The conclusion is made about the presence of statistically significant changes in the dynamics of maximum drain of the basic rivers of Belarus, basically caused by natural - climatic changes of a hydro- logical cycle. The stationary process of long-term fluctuations of the maximum drain can be marked only on separate pieces of time lines. In connection with the reduction of the maximum charges of water by the development of probable forecasts it is necessary to take into account the fact of heterogeneity of time lines of the maximum charges of spring high water in the rivers of Belarus. Prognosticated models, constructed with the use of complex Markov’s chain, in some cases give applicable results.