LAKE TAMPACUAS. Lake Tampacuas, also known as Lake Campacuas or Carter's Lake, is two miles north of Mercedes in southeastern Hidalgo County (at 26°11' N, 97°55' W). It lies within the International Boundary and Water Commission north floodway and is part of the delta system of resacas and arroyos that drain floodwaters from the Rio Grande into the Gulf of Mexico. It is about two miles long and is 700 feet wide at its broadest point. The name is said to come from that of a group of Coahuiltecan Indians who were in this area when Spanish settlers arrived in the 1700s. Indian burial grounds have been found on the lakeshore. The Llano Grande land grant, which includes the lake, was conveyed by the Spanish government to Juan José Hinojosa, chief justice of Reynosa, Tamaulipas, in 1778. The 1879 survey of the Llano Grande grant shows Tampacuas Ranch near the lake. Tampacuas Cemetery, west of the lake, contains graves of the earliest Spanish settlers and their descendents. A state historical marker identifies the cemetery.
Lake Tampacuas is within the Mid Rio Grande Delta Thorn Forest, a biotic community of more than 300 plant species. The lake was formerly surrounded by a thick subtropical forest of Texas ebony, tepeguaje, anacua, and other species. French naturalist Jean Louis Berlandier, during his residence in Matamoros from 1827 to 1851, observed jaguarundis, ocelots, and pumas in nearby brush tracts. William H. Emory, during his federally sponsored international boundary survey in 1852, recorded these cats and also jaguars. The biological richness of the Lake Tampacuas area was greatly diminished by the clearing of vegetation when the Rio Grande floodway system was built in the 1920s and 1930s. In the 1980s Lake Tampacuas was surrounded by cleared land that offered little protection for wildlife. Tampacuas Ranch and its church had disappeared. Only the cemetery remained to recall the early lakeside settlement.
Elzada U. Clover, Vegetational Survey of the Lower Rio Grande Valley, Texas (Ann Arbor: University of Michigan Botany Department, 1937). Florence J. Scott, Historical Heritage of the Lower Rio Grande (San Antonio: Naylor, 1937; rev. ed., Waco: Texian, 1966; rpt., Rio Grande City, Texas: La Retama Press, 1970).