The Navasota River rises northeast of Mount Calm in southeastern Hill County (at 31°48' N, 96°52' W) and flows southeast for 125 miles, crossing Limestone County and serving as the county line between Leon and Robertson, Madison and Brazos, and Brazos and Grimes counties before reaching its mouth on the Brazos River, six miles southwest of Navasota in southwestern Grimes County (at 30°20' N, 96°09' W). The river is dammed at various points to form Lake Mexia, Springfield Lake (in Fort Parker State Recreation Area), Joe Echols Lake, Lake Groesbeck, Lake Limestone, and Martin Lake. Tributaries of the river include Big, Little Cedar, Sand, Bowman, Panther, and Holland creeks. The river traverses flat to rolling terrain with local shallow depressions, surfaced by clay and sandy loams that support water-tolerant hardwoods, conifers, and grasses. The river was probably named by Indians, who called it or another stream in the immediate area the Nabasoto. Domingo Terán de los Ríos called it San Cypriano. Fray Isidro Félix de Espinosa named it the San Buenaventura, the name also used by the Marqués de Aguayo. Pedro de Rivera y Villalón in 1727 called the river the Navasota, the name it has been known by since that time. The community of Navasota is located in a bend of the river in southwestern Grimes County. Numerous archeological sites have been found along the river, which served early settlers as an access route into the area. By 1860, however, river transportation had declined, as the first railroad lines reached the Navasota community.