September 25, 2007
A spring is defined as a location where the water table (the top surface of the saturated zone of groundwater) reaches Earth's surface. Springs are often unnoticed in moist climates where groundwater replenishes streams as they flow toward their mouths; usually being a larger stream, lake or the ocean. But in the arid Southwest region of the U.S., there are few perennial streams. Here, streams dry up as they descend from less arid mountain sources into hot, dry valleys. Some, such as those in Saline Valley, California, flow into closed basins. Springs are of particular importance in the desert where they're often called oases. These microenvironments are critical for native wildlife. As shown above, note the classic oasis with palm trees and grasses in the middle of one of the most arid parts of the U.S. A salt playa and briny marsh occupy the lowest part of this valley.
Some small springs have escaped significant human development and have remained unchanged for thousands of years. The remote Saline Valley is a remarkable example as it is beastly hot in the summer and accessible only by about 50 miles (80 km) of very rough unpaved roads.