When the water level of Lake Titicaca is below 3,810 m (12,500 ft), the flow of Desaguadero River is so low it can no longer compensate for the massive water losses due to evaporation from the surface of Lake Poopó. At this point, the lake volume begins to decrease. At its maximum in 1986, the lake had an area of 3,500 km2 (1,400 sq mi).