As more phasor measurement units (PMUs) are installed, portions of the power grid become observable with just phasor measurements, making feasible the estimation of the state of these observable portions at much faster rates than the traditional state estimator. Although such a linear state estimator (LSE) was proposed over a decade ago, the first field implementation was completed at Dominion Virginia Power in 2013. Although this LSE is a stand-alone function not integrated to their energy management system (EMS), it demonstrated the feasibility of the LSE. In this paper, we present the design, development, and implementation of an LSE that is fully integrated with the existing EMS and can estimate the state of the extra high voltage portion of a power system at 30 times per second. Integration of the LSE to the existing EMS environment and some of the issues in the design and testing are presented in this paper. The work paved way for LSE to supply cleansed PMU data to other synchrophasor applications that are sensitive to data quality.