Lake Titicaca - Overview

Overview

The lake is located at the northern end of the endorheic Altiplano basin high in the Andes on the border of Peru and Bolivia. The western part of the lake lies within the Puno Region of Peru, and the eastern side is located in the Bolivian La Paz Department.

The lake is composed of two nearly separate sub-basins that are connected by the Strait of Tiquina which is 800 m (2,620 ft) across at the narrowest point. The larger sub-basin, Lago Grande (also called Lago Chucuito) has a mean depth of 135 m (443 ft) and a maximum depth of 284 m (932 ft). The smaller sub-basin, Wiñaymarka (also called Lago Pequeño, "little lake") has a mean depth of 9 m (30 ft) and a maximum depth of 40 m (131 ft). The overall average depth of the lake is 107 m (351 ft).

Five major river systems feed into Lake Titicaca. In order of their relative flow volumes these are Ramis, Coata, Ilave, Huancané, and Suchez. More than 20 other smaller streams empty into Titicaca, and the lake has 41 islands, some of which are densely populated.

Having only a single season of free circulation, the lake is monomictic, and water passes through Lago Huiñaimarca and flows out the single outlet at the Rio Desaguadero, which then flows south through Bolivia to Lake Poopó. This only accounts for about 10% of the lake's water balance. Evapotranspiration, caused by strong winds and intense sunlight at altitude, balances the remaining 90% of the water input. It is nearly a closed lake.

Since 2000 Lake Titicaca has experienced constantly receding water levels. Between April and November 2009 alone the water level has sunk by 81 cm and has now reached the lowest level since 1949. This drop is caused by shortened rainy seasons and the melting of glaciers feeding the tributaries of the lake. Water pollution is also an increasing concern, as cities in the Titicaca watershed grow, sometimes outpacing solid waste and sewage treatment infrastructure.