TORTUGAS CREEK. Tortugas Creek rises eight miles southwest of Batesville in central Zavala County (at 28°54' N, 99°42' W) and runs southeast for thirty-five miles to its mouth on Arroyo Negro, one mile north of the Nueces River and four miles southwest of Big Wells in northeast Dimmitt County (at 28°31' N, 99°35' W). Tortuga is Spanish for "tortoise." Three of the largest archaeological sites in Zavala County are found on Tortugas Creek. It crosses variable terrain surfaced by muddy sand and alluvial material that support scrub brush, cacti, and various grasses in the upper reaches. This changes to flat terrain with locally shallow depressions surfaced by expansive clays that support water-tolerant hardwoods, conifers, and grasses.