Culture and Ecology of Chaco Canyon and the San Juan Basin

36 Chaco Project Synthesismeasurements are within the range reported by Lyford(1979:Figure 9), who stated that the dissolved solidsin Chaco were within the 1,000 to 4,000 mg/L range.The National Park Service Water ResourcesDivision (1997) compiled available data from sixexisting databases into a report that presents baselinewater quality data on Chaco Canyon and its immediatesurrounding area (4.8 km [3 m] downstream and 1.6km [1 mil upstream from the current park units:Chaco Culture National Historical Park, the KinBineola unit, the Pueblo Pintado unit, and the KinYa'a unit). Results of pH (measured 345 times at 38monitoring stations; only 325 observations used incriteria analysis) indicated that 12 observations atseven stations were outside the pH range of 6.5 to 9.0standard units, criteria for freshwater aquatic life.Eleven observations (10 from Kin-me-ni-oli Wash)were greater than or equal to 9.0. There are still insufficientdata to make definitive statements on recentwater quality. It is likely that human activities (e.g.,those related to oil and gas exploration and development,uranium and coal mining, atmospheric deposition,livestock operations, recreational use) haveimpacted the study area. Although the criteria enteredinto the database may be flawed due to field,laboratory, or recording techniques, at present thewater does not meet the Environmental ProtectionAgency's standards for drinking water for 13 of the 18parameters or for protection of freshwater aquatic lifefor 10 of the 18 parameters as measured byinstantaneous concentration values. The reportstresses that these observations were based on recentsamples.SoilsThe soils in Chaco Canyon are affected by thealluvial material brought in through both the mainwash and its tributaries. The soil content, therefore,is not uniform across the canyon bottom. Brand(1937c:39-49) had characterized the soils in thecanyon as desert gray soils derived from local sandstonesand shales. Potash, phosphates, and nitrates arepractically lacking, but iron, sulphur, gypsum(calcium carbonate), white alkalis (sodium chlorideand sodium sulphate), and black alkali (sodiumcarbonate) are present in varying amounts. Data onsoils in general can be obtained from maps publishedby Keetch (1980: Sheets 20 and 21), but these maps aregeneral in nature and provide little detail on specificareas of the park.During the 1920s, Judd (1964:230-231) analyzed11 soil samples taken from test pit 3, located south ofPueblo Bonito between the site and his field camp.This test pit was placed in the banks of one of thepost-Bonito channels, and the samples did not comefrom cultivated fields; he indicated that they representtransported alluvium from upstream. The soils wereimpervious to water; they contained an excess ofsodium and a scarcity of soluble calcium (based on areport by J. F. Breazeale of the Office of WesternIrrigation Agriculture) and were not conducive toagricultural practices. In another study, M. Bradfield(1971:58-59) collected one sample from the floor ofChaco Canyon and 15 samples from the Hopi villages.The one from Chaco Canyon is much more saline thanthe worst one from the Hopi fields. Recent soilsurvey data by the Natural Resources Conservation isimminent (Brad Shattuck, personal communication,2003) and should provide additional information.Based on the presence of montmorillonite in thesoils that wash down the Chaco in headwaters duringmajor flood episodes, Love (1980) was not surprisedby the alkalinity reported for the soils on the canyonfloor (Judd 1954, 1959, 1964). Because of the presenceof high sodium and low soil permeability, Juddhad suggested that farmers probably used side drainagesfor growing crops, where the alluvium thatoriginated from the side canyons would have providedbetter soils for farming (D. Love 1980). Based ontheir experimental com plots, H. Toll et al. (1985)suggested that study of the south side of the canyonmay indicate this area was more reliable for agricultureover longer periods. We also need to knowmore about the chemical tolerances of the varioustypes of com and other crops that were grown(Gillespie 1985; D. Love 1977b:228). During theexperiment involving com plots that were located inseveral types of soils, corn did grow in the "blackalkali" location near Chetro Ketl. Even in the two dryyears, plants did well in relation to plants in otherlocations during the same season. H. Toll et al.(1985: 115) suggested that the fine-grained sedimentmay hold moisture better, so as to promote plantgrowth, but they also noted that the plants would havemore difficulty extracting the moisture because ofreduced permeability and increased ionic attraction.