Where milk comes from
I once heard about a survey that was conducted many years ago. A group of elementary school children were asked "if all the dairies in America shut down, where would you get your milk from?" The students responded:
"From the store."
This story illustrates a fundamental problem in society today, and that is the severe disconnect with the sources of what sustains life. As long as things are well and resources abundant then there is no problem until they are gone and it is too late.
When I recently drove through the sacred land of northern Arizona, through the Navajo reservation and through places like Monument Valley, and Canyon de Chelly, I wondered to myself:
Are we any different than the school children in the story above?
A brief history of water usage in Southern Arizona
Our knowledge of people that have called Sonoran Desert home is limited. Tucson has always been, and continues to be, a hub for human migrations. Even before the Hohokam lived here, there were people passing through here, and perhaps even calling this land home for a few generations before continuing on the path to the initial populating of Mexico and South America after a long Ice Age vacation in Beringia.
It was water, the freezing of water initially, that brought the first Americans here from Asia, and without bottled water from the local convenience store, or even water faucets, humans had to always stay near fresh water sources. It is hard to believe nowadays that Tucson was an oasis in the desert.
The Hohokam were amazing scientists. In addition to developing agriculture and farming crops that were unheard of in other parts of the world, they had to deal with the issue of watering these crops in the absence of modern technology. It is amazing what nature provides to those who observe it!
Tucson Basin
All that is required is to notice the geology of the area and to understand the concept of gravity. Gravity is free and is perhaps the most sustainable energy source, and has no emissions or carbon footprint.
While Tucson is indeed in a desert, nature provided the ultimate water-harvesting using gravity as a power source. All the rainwater from the surrounding mountains would have to make its way downhill, and would eventually make its way into the Santa Cruz river. This is were human life began in Tucson.
There have been many artifacts found from the Hohokam, especially in the area that is officially Marana, around the Ina to Avra Valley road stretch of the river. A quick glance at the map to the left reveals why this is so.
The Pantano Wash and Tanque Verde merge into the Rillito river near Craycroft and then the Rillito (which itself means river, so Rillito River is redundant) makes its way through Tucson, providing a popular biking and jogging path, a place to watch bats, and eventually to its terminus when it merges into the Santa Cruz river south of Orange Grove road. Just north of Orange Grove road you have the Cañada del Oro merging with the Santa Cruz river after a long journey from the mountains near Oracle.
At this point near Ina road, 5 rivers have become 1, and this is the only way out for any water in the Tucson area. This is also why the master-planned communities in this area are in danger of the next big flood. In the flood of 1983, the whole area now known as Continental Ranch was under water. Luckily Tucson hasn't been flooded to such an extent since these houses have been built, and efforts have been made to get the water out of this region quickly also, which ended up flooding some communities in Marana, such as Berry Acres just three years ago in 2006.
A lot has changed, from the current inhabitants of master-planned communities to the original Hohokam, and we can learn a lot from both in order to plan for our future.
The gravity of the problem
The main difference would be how water was accessed and used. An understanding of gravity makes all the difference. In addition to all the water flowing downstream from all over Tucson, the Santa Cruz river is also bringing water from further south, from Mexico and the mountains along the international border.
Interesting trivia knowledge: The only US river to enter Mexico twice is the Santa Cruz river.
All this water is brought to us using the force of gravity. The area to the south of Tucson is at a higher elevation, so this works out nicely. But what happens when the slope is not so steep? This last point is crucial in the history of the Santa Cruz.
Nature is the ultimate reality simulator. Over thousands of years the river has learned to flow in the direction it does, and the river also changes the flow of itself. This is because as the water runs, it digs into the ground. An ultimate illustration of this is the Grand Canyon. The water is forced to flow a mile deep, but the water is altering its own path since it is still carving out the canyon.
The Santa Cruz is no different, and maintaining this natural flow is important to having a flowing river.
Gravity can also be used in a different way. You can plant your crops near the base of a mountain, and after a monsoon rain, you can direct the water to your crops easily, without the use of any pumps or modern technology.
The Hohokam are also famous for their system of irrigation canals in the Phoenix area. This was smart of them, but this was not sustainable, and after a long drought perhaps, the Hohokam left, leaving behind their canals. The more I think about this, the smarter I think the Hohokam were. The question becomes:
Is it smarter to force a place to be "sustainable," or to move to a place that is already more sustainable?
The answer the Hohokam came to was to abandon the towns along the rivers in Southern Arizona, and move elsewhere. This decision allowed the Santa Cruz to continue flowing, and it flowed year-round until the turn of the 20th-century. Ironically, the decline of the Santa Cruz is due to a fellow by the name of Sam Hughes, who is honored today by having one of the most sought out communities for university folk to live named after him. Sam Hughes neighborhood is directly adjacent to the UA on the east side.
The following informational sign can be found along the river:
Today the usually dry bed of the Santa Cruz River lies some 20 feet below the top of its banks. Due to a combination of human errors and natural catastrophies in the late nineteenth century, the river now flows only during seasonal floods. In 1887, Samuel Hughes attempted to increase the water supply to his fields north of St. Mary’s Road. He built a new, deep ditch to tap the subsurface flow of the river. Large floods during the next four years caused this ditch and others to downcut and errode rapidly. The ultimate result is the deep, dry channel of today. The effect on irrigated agriculture was profound. Canal intakes were stranded high above the river bed, and canals were severely damaged. Gravity irrigation with surface water was no longer possible.
You can see this for yourself today. A walk along the river reveals a deep channel built into the ground, and where the level is no longer lower than upstream, the river simply takes its operations underground...
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