During the past years huge amounts of resources in the environmental domain have been published on the internet. To facilitate search and discovery of relevant data among an ever increasing mass, the use of tags has been suggested. Yet, the use of non-formal tags for annotating resources allows simple categorization and search capabilities, but it does not provide the means to create cross-domain annotations. On the other hand, ontologies are a shared and formal conceptualization of a given domain and they can be used to formalise tags. The use of formal semantics for tagging allows taking advantage of the reasoning and inference power of the ontologies to create richer resource annotations enhancing the discovery process. In the environmental domain there is a clear need of frameworks and tools allowing formal tagging and discovery. In this paper we discuss about the definition of a Semantic Framework helping the tagging and discovery process of environmental resources. Moreover, we also report on the definition of a model to describe environmental resources allowing cross-domain annotation and search.