The NRL (Naval Research Laboratory) project has been monitoring the middle atmospheric water vapor profile, using the Naval Research Laboratory ground-based Water Vapor Millimeter-wave Spectrometer (WVMS) instruments. These 22 GHz spectrometers are making measurements as part of the Network for the Detection of Atmospheric Composition Change (NDACC). Instruments have been deployed at Table Mountain since 1992, and the Table Mountain site has been used to intercompare all new WVMS instruments which have been deployed since 1992. Other WVMS instruments currently operate at Mauna Loa, Hawaii, and Lauder, New Zealand. Measurements from the Table Mountain instrument have played an important role in several scientific studies, including the discovery of a large increase in middle atmospheric water vapor from 1991-1997 [Nedoluha et al., JGR 103, 3531-3543, 1998].