A designer uses the stream gauge analysis findings for design when there is sufficient years of measured or synthesized stream gauge record. A preferred method for analyzing stream gauge data is the Pearson Type III method. Such approach is supposed to be possible because of the assumption that given sample is derived from stable statistical population. But it has been established theoretically that runoff from about half European territory of Russia can not be statistically stable. This fact was not refuted visually by this investigation of existing runoff records. But in the future it is necessary to perform such analysis using statistical criteria.