sentences:  The Spanish made the first recorded anthropogenic changes to hydrology in the San Juan watershed, which included excavating irrigation channels, diverting water from streams, and channelizing and changing course of streams.Grazing animals introduced by Europeans, mainly cattle (and later sheep, after a drought decimated the local cattle ranching industry), consumed native grasses and left hillsides exposed and prone to erosion.The origin of the name of Arroyo Trabuco "(Spanish