Regional hydrogeological models (HM) are founded on geological and geographical information of a country. By processing this information, HM can provide complex spatial distributions of groundwater heads and flows, data on groundwater discharge into rivers and lakes as their joining with groundwater bodies. Appliance of the regional HM considerably improves quality of the country sustainable water management, because HM provides consolidated knowledge on interaction between surface water and groundwater and on their accessible resources. For solving practical problems of environmental protection and recovery, local HM are applied. They are created by completing data of regional HM by more detailed information. In 2011-2015, scientists of Environment Modelling Centre (EMC) of Riga Technical University (RTU) have developed four successive versions of the regional HM of Latvia: LAMO1→LAMO2→LAMO3→LAMO4. The current version LAMO4 has been tested and approbated in 2016-2018, by carrying out the research on nature processes on regional scale and also by using local HM. Presently, the information regarding development and appliance of LAMO4 are available of the RTU EMC web site. In the near future, this information, as the set of geospatial data, will be inserted in the portal geolatvija.lv in the section “hydrogeological data”. By using information provided by LAMO4 on the groundwater discharge in rivers, it will be possible to develop the computer model for the research of pollution processes in the river network of Latvia. In the future, the development LAMO4→LAMO5→LAMO6 will considerably improve credibility and quality of data provided by modelling. For the next version LAMO5, the model set of lakes and rivers will be increased and the plane approximation step 125 meters will be used (LAMO4 has the step 250 meters). The version LAMO6 is the expansion of LAMO5 by adding information on groundwater quality and by providing advanced open data options. The research on LAMO development was supported by the European Regional Development Fund (2011-2012) and by the Latvian State Research Program EVIDEnT (2014-2018).