The CORNARE region, located in Antioquia (Colombia), required a redesign of its water quantity, quality, and sediment-monitoring network, in order to collect convincing data to help decision-makers to respond to different technical and environmental issues. This paper proposes a methodology which is based on secondary information and which employs Geographical Information System –GIS- tools and knowledge of the region, given that historical data are unavailable in most of the region. Although the main methodology, which applied physical, anthropic, and economic factors was the same for all networks, specific strategies were used for water quantity, quality, and sediment networks in the region. These used expert criteria and weight distance methods. The results were satisfactory. Macro-location was implemented for the sites monitored in the CORNARE region, and this indicated that the proposed methodology was adequate for tropical Andean watersheds, where historical data were insufficient and did not permit the use of more complex techniques. This methodology integrates water quantity, water quality and sediment in an integrated hydrological monitoring network.