In this paper, we describe the case for creating and managing "virtual sensors" for near-real-time sensor data aggregation and transformation with a case study in a watershed near Chicago. We explore various levels of abstractions of "virtual sensors", and how the virtual sensor concept and digital watershed tool can help facilitate community participation and build consensus on using and re-purposing the near-real-time data. We describe our proposed approach on aggregating NEXRAD data and on-ground in-situ precipitation gage data in near-real-time for anomaly detection purpose.