English: Total column water vapor measured at 940 nm and 830 nm (reference wavelength) using the same sun photometer at solar noon from 1990 to 2016 at Geronimo Creek Observatory. The trend is slightly down (app. -1.5 mm/decade). Calibration: NOAA GPS data from Galveston, TX, and Mauna Loa Observatory, HI. Measurements are made at or near solar noon when clouds are not before the sun. Water vapor is the key global warming gas. The 1997-98 peak occurred during a major El Nino. No such peak occurred during the 2015-16 El Nino (at least so far). The general shape of the data resembles the global water vapor plot in NASA's ongoing NVAP study.