Astronauts aboard the Space Shuttle and Space Station have tracked regional environmental changes spanning decades. Lake Chapala, Mexico’s largest lake, serves as one example of an area experiencing significant changes that have been well documented from space. Over the past twenty years, the lake’s water levels have decreased in conjunction with increasing development from the fast-growing city of Guadalajara.
The Great Salt Lake of northern Utah is a remnant of glacial Lake Bonneville that extended over much of present-day western Utah and into the neighboring states of Nevada and Idaho approximately 32,000 to 14,000 years ago. The north arm of the lake, displayed in this astronaut photograph from April 30, 2007, typically has twice the salinity of the rest of the lake due to impoundment of water by a railroad causeway that crosses the lake from east to west. The causeway restricts water flow, and the separation has led to a striking division in the types of algae and bacteria found in the north and south arms of the lake.
Heavy winter and spring snowfall provided much-needed meltwater, but the effects of long-term drought mean the lake is nowhere near its highs from the 1980s and 90s.
Ongoing drought and diminished snowpack in the Rockies have combined with increasing demands downstream to cause the great reservoir to drop to historically low levels.