Explore additional content related to The Flow of Water and Time: Irrigation Longevity and Social Change among the Lower Salt River Hohokam, Chris Caseldine’s November 10, 2020, Archaeology Café Online presentation.
Extended Q&A with Chris Caseldine:
Q: Is there any evidence of that changing channels in the Salt River that may relate to how canals were constructed and maintained?
A: The lower Salt River is known to have shifted parts of its main channel historically, because of flooding. River aggrading, as it is called, appears to have been significant along the middle Gila River in the past, but is less well understood along the lower Salt. The archaeological record provides us with a general view of the past, so we rely on finding patterns or exceptional events. It is extremely difficult to separate individual flood or channel shift events in the depositional history of rivers, including the lower Salt. The deposits tend to blend together. In a few cases, like the late Colonial/early Sedentary extremely large flood (ca. 900 CE), a flood deposit is found covering a canal. If the 1891 flood provides insights for the extremely large flood, then it is conceivable that the Riverview and Scottsdale systems located their intakes where they did because the river had dramatically shifted its main channel.
Q: Was that 300,000 CFS flood in 1891?
A: The peak of the 1891 flood (February 19th) was 300,000 cubic feet per second or cfs. The floodwaters extended two to three miles from the riverbed. The late Colonial/early Sedentary extremely large flood may have been as much as 400,000–450,000 cfs. As a point of reference, before the construction of the Roosevelt and other dams along the Salt River, annual flooding was 8,000–12,000 cfs. Those floods destroyed weir dams and headgates. Approximately every 14 years, floods of 100,000 cfs occurred, damaging earthen canals.
Q: The level of flooding on the Salt is extraordinary to me. Record levels on the Colorado River was 500,000 CFS. These are extraordinary levels. How did you determine the high levels of floods for the Salt?
A: Jonathan Fuller (U of A thesis 1987) determined that a very large flood likely occurred around 900 CE based on flood deposits in Hohokam canals and the height of flood deposits in the Salt River canyon that appeared to have the same dating (slackwater analysis). Keith Katzer is the first to my knowledge to propose an extremely large flood significantly shaping Hohokam society this early in the Hohokam history.
Q: How do extreme drought events also factor into the timing of social changes during the important transitions that you have pointed out?
A: My water sufficiency analysis indicated that some water reached the lower Salt River valley through time, based on the tree-ring work by Donald Graybill and others. Water became more problematic during the early Classic Period (1100/1150–1300 CE), but the cause seems to be that farmers in the valley had reached the upper limits of what could be irrigated consistently, in terms of the number and size of irrigation systems that may have operated. The streamflow reconstruction for the Gila River seems to have more issues with long periods of low flow (droughts) than the Salt River. Gary Huckleberry and others have discussed the Salt and Gila rivers being subject to different climatic regimes. The flow of the Salt River is influenced by the El Niño Southern Oscillation (ENSO).
Q: Any indication of damming to manipulate river levels to facilitate irrigation?
A: The Hohokam likely used weir dams that were made from boulders and other fill items with a wickerwork of logs and branches. These kinds of dams were constructed into the twentieth century in parts of the Phoenix Basin.
Q: Wondering about the mechanics of headgates, what are these made of? How managed? Did flooding damage temporarily/permanently?
A: Hohokam headgates were long destroyed by the time Anglo farmers began to irrigate. The stratigraphy in large main canals shows that the Hohokam were likely regulating water flow into the irrigation systems. Smaller gates have been documented. Those gates had logs or thick branches placed vertically to act as support posts. Around this was fill (pottery pieces, rocks, and other items) sandwiched between retaining walls and faced with interwoven branches on the sides of the canal. An opening was at the center to allow water to flow through. Some kind of plug or gate may have been placed in the opening when river water was not needed, such as during canal cleaning. They likely had to be replaced annually or after flood events.
Q: I have read that many of the CAP canals that pass through the Phoenix area make use of the Hohokam ancient canals. To what degree is that true?
A: The earliest canals that Anglo-Americans used in the lower Salt River valley were dug-out Hohokam canals. Many of the older canals that cross the valley follow the same path as the Hohokam ones. A large portion of the Grand Canal that runs past Pueblo Grande today was set on top of a large Hohokam main canal. Some of the ancient canals were as much as 15 or more feet deep.
Q: What are the impacts that our freeway system has had on the ancient canal system?
A: Archaeological excavations carried out before the construction of freeways gave archaeologists the chance to document and study Hohokam canals in ways that were not possible otherwise.
Q: Can any of these Hohokam canals be seen today? I’ve been to Park of the Canals and seen the ones near Pueblo Grande. Are there others?
A: The canals at the Park of the Canals in Mesa, Arizona, and Park of the Four Waters next to Pueblo Grande are the best preserved. Agricultural and urban development and floods have erased evidence of other canals from the surface, but they are not gone. Buried canals are still intact below the ground. Even today, if you look at Google Earth, there are areas where you can see the buried canals.
Q: Were crops planted in straight rows?
A: It does not seem that ancient crops in the Hohokam region were planted in straight rows. Evidence from the Las Capas site in Tucson and historical accounts indicate that planting holes and mounds were used.
Q: What was the farm plot size for growing cotton? Was it grown on beds or flat?
A: Good question. It is one of the many questions we have for the crops Hohokam farmers grew. Historically, the Akimel O’Odham grew cotton in dedicated fields. On average, families had two to five acres of agricultural land. The cotton they grew took much longer to reach maturity than maize and other crops. Pushing this insight into the past, the Hohokam may have had two harvests of maize and one harvest of cotton each year.
Q: I saw a talk by someone from Crow Canyon about farming in SW Colo., specifically McElmo Canyon area. She grew her own crops to find out why people seemed to move farming locations about every 5–10 years. Her own gardens revealed that there was often a buildup of borax-like chemicals, so moving often was common. Is there anything similar with the Hohokam or does the flooding and regular irrigation make that not happen?
A: Studies of ancient agricultural fields along the lower Salt and middle Gila rivers have found that the Hohokam were able to stop soils from accumulating excessive salts, also known as salinization or alkalinization. I am unfamiliar with the McElmo Canyon area, but I suspect ancient people there practiced rainfed agriculture. The amount of movement documented among Ancestral Puebloan groups is not seen in the lower Salt River valley. Hohokam farmers appear to have irrigated the same area of land for hundreds of years. The amount of water that was applied to fields seems to have been enough to flush salts in the soil.
Q: Would there have been competition for water, rather than cooperation, when streamflows were low? How would this have affected Hohokam society?
A: There is no evidence that a valley-wide irrigation authority existed. Each Hohokam irrigation system likely managed its own supply of water. There are extensive cross-cultural studies of societies that practiced traditional forms of irrigation that indicate the longevity of a system depends on cooperation. Farmers complain that everyone else is stealing water, but rules governing irrigation systems seem to work well enough to make sure members do what they are supposed to do. In irrigation systems that persist through time, the farmers cooperate the amount they need to. Irrigation tasks like cleaning canals seems to strengthen bonds between members. There is no evidence that Hohokam irrigation systems went to war with each other over water, but any violence likely would have been small and not easily identifiable in the archaeological record.
Q: How did political control work if there were few strong pathways to power like irrigation and surplus control visible in the Hohokam archaeological record? Was there a powerbase to control?
A: The nature of power and control in irrigation is beyond what I can discuss here. There is evidence that some members of Hohokam society were wealthier than others, but it did not translate into central authority. Why is an unresolved question.
Q: What can you surmise about the social organization of the canals? Consider Steven Lansing.
A: Hohokam irrigation was likely organized by farmers for farmers. As Lansing’s work shows, political elites have very little control over the function of irrigation systems. The Balinese kings were more likely to destroy rival irrigation systems than to seize control. There are exceptions, but by and large, farmers control their systems. Political elites often restrict their involvement with irrigation to demanding taxes/tribute and/or labor.
Q: Who was colonizing in the colonial period and where did they come from?
A: The Hohokam time periods—Pioneer, Colonial, Sedentary, and Classic—were defined during a time when archaeologists thought about the past in a very different way than we do now. The terms follow a narrative of progress. People came into an “empty” area (Pioneers), others followed (Colonial), generations of families settled down in the area (Sedentary), and then a florescence of art and culture happened (Classic). We now know that this is flatly wrong. People were living in the Phoenix Basin and elsewhere long before and after the Hohokam cultural sequence. The terms continue to be used because they are tied to cultural traits like pottery style and the types of houses people built. Rather than a beginning and an end, the Hohokam periods are points along a continuum that continues today through their descendants.
Q: When did the term “Civano” begin to be used?
A: The use of the term Civano to identify the late Classic Period (1300–1450 CE), represented by adobe compounds and Salado Polychromes (Roosevelt Red Ware), appears to begin in association with the excavation of Snaketown along the middle Gila River by Gila Pueblo in the 1930s (Gladwin 1937). The Civano phase is specific to the Phoenix Basin. The late Classic Period in the Tucson Basin is called the Tucson phase, the Gila phase in the Tonto Basin, and the Safford phase in the Safford Basin.
Q: Any evidence of the Ancestral Puebloans arriving during the Classic Period?
A: It is unlikely. Pottery, architecture, and other cultural items look very Hohokam in the Phoenix Basin. The movement of people during the Classic Period seems to be between the middle Gila and lower Salt rivers.
Q: Was there any influence on the canal systems by the Salado influence?
A: At one time, archaeologists thought that the Salado were a group of people that invaded the Hohokam region. Increasing data showed that the idea was wrong. Salado is an ideology or belief system that spanned the Hohokam region and other parts of the Southwest. As former Archaeology Southwest Preservation Fellow Lewis Borck has pointed out, Salado is not one thing. It differed by location, and some people seem like they did not want to take part. Hohokam irrigation systems in the lower Salt River valley transcend time and were not linked to any particular influence like Salado or earlier ballcourt rituals. Some archaeologists believe that elites living at platform mounds controlled the irrigation systems, but I disagree based on available archaeological evidence and cross-cultural studies of societies that practiced traditional forms of irrigation agriculture.
Q: Sheep?? I thought they came in with the Spanish?
A: Bighorn sheep. A complete animal was found north of Phoenix in a pithouse. The archaeologists thought it may have been hanging for processing.
Read Archaeology Southwest Magazine (Vol. 31, Nos. 2 & 3), “Phoenix Underground,” available here.
- The Hohokam Archaeology of the Phoenix Basin. Vol. 21, No. 4 (Fall 2007)
- Fact Sheet: Who or What Is Hohokam?
- Video: Phoenix Archaeology Under the Freeways
- Blog Post: Societal Change in the Past
Abbott, David R. (editor)
2003 Centuries of Decline during the Hohokam Classic Period at Pueblo Grande. University of Arizona Press, Tucson.
Abbott, David R., Scott E. Ingram, and Brent G. Kober
2006 Hohokam Exchange and Early Classic Period Organization in Central Arizona: Focal Villages or Linear Communities? Journal of Field Archaeology 31(3):285–305.
Caseldine, Christopher R.
2020 Hohokam Irrigation Longevity and Agricultural Success in the Lower Salt River Valley, Arizona. Ph.D. dissertation, School of Human Evolution and Social Change, Arizona State University, Tempe.
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2017 Classic Period Hohokam. In The Oxford Handbook of Southwest Archaeology, edited by Barbara J. Mills and Severin Fowles, pp. 353–380. Oxford University Press, New York.
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2006 Hohokam Irrigation Communities: A study of Internal Structure, External Relationships and Sociopolitical Complexity. Ph.D. dissertation, Department of Anthropology, Arizona State University, Tempe.
Hunt, Robert C., David Guillet, David R. Abbott, James M Bayman, Paul R. Fish, Suzanne K. Fish, Keith Kintigh, and James A. Neely
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