The document discusses the development and testing of a synchrophasor data validation and conditioning application using linear state estimation (LSE) for utilities in the Western Electricity Coordinating Council (WECC) region. It describes the modeless and LSE-based approaches used by the application to validate and condition synchrophasor measurements. Testing of the application was conducted using historical and live synchrophasor data from Bonneville Power Administration's (BPA) system. The results demonstrated the application's ability to detect and replace bad data in real-time. Lessons learned and future work areas are also outlined.