Water is a vital natural resource, particularly in the arid southwest. Most of the flow of the Colorado River through Grand Canyon originates in the Rocky Mountain region. From its origin to its mouth in the Gulf of California, many hands have claimed the Colorado waters for such purposes as irrigation and water supply.
The Colorado River within the boundaries of Grand Canyon National Park drains an area of approximately 41,070 square miles. The major perennial streams feeding into the Colorado (such as Kanab and Havasu creeks, the Little Colorado River and the Paria River) are related to large perennial spring systems on both the north and south sides of the Canyon. However, the majority of water sources are intermittent or ephemeral in nature. The availability of water in these individual systems is closely related to geologic structure, seasonality and annual precipitation. Knowledge of all water sources within Grand Canyon is incomplete. A partial inventory was done in 1979 over a 1,881 square mile area of the park which found 57 perennial water sources, 21 of which are streams and 36 which are seeps. Specific geologic layers, such as the Muav limestone, are the most common sources for these perennial waters.