At an average elevation of 3,812 meters (12,507 feet), Lake Titicaca is one of the highest lakes in the world. The lake is positioned between two major ranges of the Andes Mountain chain and has very limited drainage. The limited outflow of the lake allows for the accumulation of nutrients derived primarily from surrounding communities’ agricultural and sewage waste. The increased nutrient levels can lead to plankton blooms. This astronaut photograph, taken from the International Space Station, captures two such blooms along the eastern shoreline of the lake.
Algae covers much of Lake Erie’s western basin in these images, taken in early October 2011, when one the the largest blooms in recent decades spread across the lake.