To obtain square meter (m) cubic meter (m3) cubic meter per second meter (m) kilometer (km) (rr,3 /s) National Geodetic Vertical Datum of 1929 (NGVD of 1929): A geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called "mean sea level." VI WATER QUALITY OF BELTON LAKE, CENTRAL TEXAS