sentences:  Somewhere north of Brgy.Tumana in Marikina marks a point at which an American Colonial Era levee shifted the flow of Marikina River west, away from the population center of Sitio Bayanbayanan (now known as "Concepcion Uno"), where erosion had been a problem.The construction of a levee left behind a remnant waterway now known as "Patay na Ilog" (literally "Dead River", referring to the former path of the river) where the original path of the river once traversed, which rejoins the Marikina River just south of Tumana Bridge.