The methodical basis of geoinformational monitoring of water use is described, its specificity and ability to assess water management indicated. The GIS of monitoring water use in the Baikal basin on the basis of official statistics is presented. The technological structure of GIS is substantiated, its subsystems were described. The structure of the regional water use database was developed, and its fragments represented. The technique of geoinformational monitoring water facilities and processes was developed. The example of qualitative and quantitative assessment of water use is given.