Many of the qualities that characterize geographic regions are vague and granular in their nature. In many quality-based classification and delineation systems for geographic regions, therefore, there is a trade-off between the possible precision of the quality-based delineation and the scientific sophistication of the quality-based classification of geographic regions. This poses a dilemma for the US Geological Survey's National Map, whose purpose is to provide various integrated classification and delineation systems that can serve a wide range of users. Some users need precise delineation systems, while others need sophisticated classification systems. Many users are required to use and to produce data that are not affected by the above trade-off and that can be integrated in consistent ways. This article discusses an ontologybased solution to this problem, presented in the specific context of systems for classifying and delineating eco-regions and eco-zones.