San Cristobal Wash facts for kids
The San Cristobal Wash is a special kind of riverbed in the desert. It's called an ephemeral wash, which means water only flows through it after it rains a lot. Most of the time, it's dry! This wash is located in the San Cristobal Valley in the very dry southwestern part of Arizona. It flows north and eventually reaches the Gila River.
This area is one of the driest places in North America, similar to parts of Death Valley or the Chihuahuan Desert.
Where the San Cristobal Wash Flows
The San Cristobal Wash follows the direction of the mountains and valleys in the region, which generally run from northwest to southeast. Many smaller washes and dry streambeds, called arroyos, join together to form the San Cristobal Wash. It enters the San Cristobal Valley from the south.
However, the wash doesn't flow all the way through the valley. It disappears about 8 kilometers (5 miles) south of the Gila River. This happens because the water soaks into the ground or evaporates in the hot desert air. Most of the wash is in Yuma County, but some parts of its drainage area, especially from the Growler Valley, reach into western Pima County.
How Water Reaches the Wash
The southern parts of the San Cristobal Wash connect to the ends of two valleys. This means the water flow can split in two directions, a process called bifurcation. On the west, it drains the Mohawk Valley (Arizona) towards the southeast. On the east, it drains the southern part of the Growler Valley, where water flows south into the headwaters (the very beginning) of the San Cristobal Wash.
Several drainages from the southeast combine to form the San Cristobal Wash as they flow northwest. One important one is the Growler Wash, which comes from the Growler Valley east of the Granite Mountains (Arizona). East of that, there's Daniels Arroyo. This arroyo flows next to the Tenmile Wash Drainage in the Childs Valley of southern Arizona, in Pima County. The Tenmile Wash Drainage is the next area that sends water into the Gila River, just before the Gila River turns north.
Neighboring Desert Areas
Downstream from the San Cristobal Wash, the next and final major area that drains into the Gila River is called the Lower Gila Watershed. To the southeast of the San Cristobal drainage is the Tule Desert Drainage. The Tule Desert (Arizona) is unique because its water drains south into Sonora, Mexico, instead of flowing north towards the Gila River.
