The possibilities to use optical methods for estimating the parameters of the dispersed spatial structure of water ecosystem of loess water bodies are considered, using the Lake of Khanka as an example. It was shown that proximate optical methods could be used to estimate the average size of organic-mineral detritus, their boundary surface, the concentration of mineral suspension particles and their specific surface, the average distance between particles, and the common concentration of organic matter. The methods of instrumental valuation of contact boundary characteristics, which were used, allow proceeding to direct investigation of quantitative characteristics when studying the processes going on in boundary zones. The evaluation of number bacterio- and phytoplankton, carried out with the help of standard hydrobiological methods, has allowed estimating a structure of their space distribution in waters of lake. The data on space distribution bacterioplancton, phytoplankton and particles of a mineral suspension enable more precisely to determine the energy expended bacteriocells at their passage from free in an attached condition and cells phytoplankton at their vertical migration.