Beginning in August 2016, the District will start implementation of the use of a new vertical datum, the North American Vertical Datum of 1988 (NAVD88). In the past, the District has used the National Geodetic Vertical Datum of 1929 (NGVD29). The new datum will result in a downward shift of between 0.64 to 0.90 feet depending on location. There is no change in the actual river level, only the value used to represent the level is different. The full conversion is expected to be complete by November 1, 2016.