Many kinds of environmental data are nowadays publicly available, but spread over the web. This paper discusses using the Sensor Observation Service (SOS) standard of the Open Geospatial Consortium (OGC) as a common interface for providing data from heterogeneous sources which can be integrated to a user tailored environmental information system. In order to allow for providing user-tailored and problem-specific information the adjusted SOS is augmented by a semantic layer which maps the environmental information to ontology concepts. The necessary information fusion from different domains and data types lead to several specific requirements for the SOS. Addressing these requirements we have implemented a SOS which still conforms to the OGC SOS 1.0 standard specification. The developed SOS has been integrated in a public available demonstrator of our personalized environmental information system. Additionally this paper discusses future consequences for the SOS, caused by the recently published SOS 2.0 specification.