Flooding of soils by waters of storage lakes results in certain changes in humus content and composition in submerged soils. The content of humus decreases especially in meadow soils of deep-water zones, the C:N ratio increases; the proportion of the most mobile fractions of humic and fulvic acids is reduced whereas the sum of humic and fulvic acids grows to the expense of nonhydrolizable residue; some accumulation of lipids is observed. Ground sediments are characterized by the increase in organic matter content.