The Rancho Viejo Floodway, which protects the city of Brownsville from flooding, is divided into two branches in southern Cameron County. The eastern branch empties (at 25°58' N, 97°24' W) into San Martin Lake and various resacas, while the branch northwest of the city drains into the Rio Grande (at 25°59' N, 97°36' W). Rancho Viejo Floodway, east, is four miles north of the Brownsville Ship Channel in extreme southeastern Cameron County and is a mile long. The western branch is in extreme southwestern Cameron County about six miles northwest of Brownsville and is about three miles long. The local flat to rolling terrain is surfaced by deep to shallow, sandy to clayey loams that support scrub brush and cacti.