Río Pinotalca is a coastal river located in the Maule Region of Chile, originating on the western slopes of the Cordillera de la Costa, west of the city of Empedrado. The river flows in a generally westward direction before emptying into the Pacific Ocean. Known historically by multiple names — including Loanco in its lower reaches and Empedrado in its upper course — the river drains a distinct coastal watershed (Sub-basin 074-00) that sits south of the Río Maule mouth and north of the Región de Ñuble boundary. Its coastal origins and Pacific outlet give it a character quite different from the Andean rivers of central Chile, with the Cordillera de la Costa providing its headwaters rather than high mountain snowpack.