LAVACA RIVER. The Lavaca River rises in the far northeastern corner of Gonzales County (at 29°38' N, 97°08' W) and flows southeast for 115 miles, crossing Lavaca and Jackson counties, to its mouth on Lavaca Bay in northern Calhoun County, 1½ miles north of Point Comfort (at 28°42' N, 96°35' W). The river, which drains an area of approximately 2,280 square miles, was originally described by René Robert Cavelier, Sieur de La Salle, who named it Rivière de Les Veches, or “Cow River,” because of the buffalo in the area. The Spanish translated the name to Lavaca. Even though the stream is classed as intermittent because it depends on rainfall rather than permanent springs for its water, the average annual flow is about 600,000 acre-feet, and heavy rains bring frequent flooding as far upstream as Hallettsville. During the nineteenth century the river was normally navigable to Texana, thirty miles above its mouth. According to legend the Pride, flagship of pirate Jean Laffite's fleet, was scuttled in the Lavaca near its mouth when pressured by an American revenue cutter.
Full article on the Texas State Historical Association's Handbook of Texas Online