The Lavaca River (i/ləˈvɑːkə/ lə-VAH-kə) is a river in the U.S. state of Texas. It begins in the northeastern part of Gonzales County, and travels generally southeast for 115 miles until it empties into Lavaca Bay, which is a component of Matagorda Bay.
The river's name is a corruption of Rivière des Vaches ("Cow River"), by French explorer René-Robert Cavelier, Sieur de La Salle. The flagship of Jean Laffite's fleet was alleged to have been scuttled in the lower part of the river.
Only the portion of the watershed and associated water resources located in Jackson County are managed by the Lavaca-Navidad River Authority, which was established in 1941.