The coding system of the catchments of Slovenia and the ecohydrological areas of Slovenia provide the informational bases for the development of water management and implementation of the EU Water Framework Directive (WFD). The measurements on the Dragonja catchment enabled a new approach in calculating soil erosion and new views regarding the influence of forests on the water cycle. The increase in forested areas of Slovenia changes the water balance and reduces surface waters. The development of a synthesis method of determination of ecomorphological water quality by means of analysing the state of the Dragonja River will enable a development of a methodology for determination of quality as a responsibility of Slovenia, in accordance with the EU Water Framework Directive. The making of the Slovenian part of the multilingual international hydrological Unesco dictionary with more than 2000 synonyms enables a unified use of professional expressions in terms of hydrology and technical translations into world languages. Hydrological and hydrotechnical analyses of the causes and events connected with large landslides in Slovenia (Stože, Koseč) provided a basis for an integrated and safe spatial management and safety of people in the framework of remediation programmes. The co-operation in making the location plan for the HPP on the Lower Sava River has enabled the introduction of modern solutions of the influence of changes in the water regime over the environment. Hydrological measurements for the needs of the Sava River HPP's and models of hydrological forecasting enable a more efficient use of HPP objects in power production.