The work is devoted to the water balance assessment of the Lake Ilmen (North-West of Russia). The values of precipitation, runoff and evaporation for the Ilmen basin were mapped.  Alisa Dmitrievna Prokopenya is a thoughtful and efficient student with high potential. As part of her work, she summarized measurements at meteorological and hydrological stations and made an attempt to improve the reliability of water balance calculations through the use of grid archives of hydrometeorological information. Mapping of water balance elements is carried out at a high level by means of  GIS-technologies. The objective has been achieved. The work fully complies with the requirements established for graduate qualification of undergraduate students. I suppose that the work can be rated "excellent".