 From its source in the Parinacota wetlands the river flows west.The spurs of the "Cordillera Central" (also known as "Chapiquiña") form an obstacle impossible to pass through, forcing the river's course southward.In the vicinity of Wallatiri volcano, the Lauca turns again, now eastward crossing from Chile into Bolivia at the latitude of "Macaya", at an elevation of 3,892 m asl and with a flow rate about 2,6 m³/s.