Skip Navigation Links

The State of Natural and Cultural Resources in the Colorado River Ecosystem:

JUNE 30, 1999 DRAFT REPORT
Grand Canyon Monitoring and Research Center
Flagstaff, AZ 86001
Updated: 30 June 1999

Table of Contents

Cultural Resources

Introduction

Cultural resources along the Colorado River corridor include archaeological sites and traditional cultural resources such as springs, landforms, sediment and mineral deposits, and traditional plant locations and animals. All of these resources have the potential to be affected by the operations of Glen Canyon Dam. The ultimate goal of the cultural resource efforts related to Glen Canyon Dam operations is in-situ preservation, with minimal impact to the integrity of the resources and when preservation is not possible data recovery efforts, as appropriate.

Top of Page

Background

The current information concerning cultural resources is based on a number of previous investigations within the Colorado river corridor in the Glen and Grand Canyons conducted by the NPS and various tribal groups. Comprehensive overviews of previous investigations are included in Ahlstrom et al. (1993) and Fairley et al. (1994).

Past Studies: Archaeological remains were first noted in the river corridor by Euro-Americans during the Powell expeditions in the 1800s (Powell 1875). Traces of archaeological remains were noted in the vicinity of Bright Angel Creek and the Unkar Delta area. In later years, archaeological investigations were noted in the river corridor and on the rims of the canyon (Hall 1942; Haury n.d.). In the 1950s and 1960s, investigations became more focused under the direction of the NPS, in part due to anticipated dam development in areas of the Canyon (Euler 1967; Euler and Taylor 1966; Taylor 1958). In the late 1960s and early 1970s the School of American Research and the NPS conducted excavations in the river corridor and adjacent areas to investigate the prehistoric settlement pattern (Jones 1986; Schwartz 1965; Schwartz et al. 1979, 1980, 1981). Together, these studies provided the initial information that suggested that numerous cultural resources existed within the river corridor.

EIS Studies: Intensive archaeological inventories were conducted by the NPS during 1990 to 1991 in preparation of the GCDEIS to assess a range of dam operations (Fairley et.al 1994). These inventories located approximately 475 sites within the assessed area extending from Glen Canyon Dam to Separation Canyon, about 255 river miles and up to the 300,000 cfs flood level. Of the sites within this area, approximately 336 had identifiable impacts that were believed to be related to dam operations. Impacts were categorized as direct, indirect, or potential. Direct impacts included sites where inundation or bank cutting had occurred within the site in recent years. Indirect impacts included: 1) bank slumpage or slope steepening adjacent to the site, 2) arroyo cutting or other erosion phenomena related to base level lowering from river eroded sediments within the site, and 3) effects of visitor impacts at sites due to recreational use patterns. Potentially impacted sites include those within the 300,000 cfs flood level without direct or indirect impacts currently identifiable.

Participating Native American tribes have also conducted cultural resource inventories to identify resources that have important cultural values to them. These studies were conducted by the Hopi Tribe, the Hualapai Tribe, the Navajo Nation, the Southern Paiute Consortium, and the Zuni Pueblo during the development of the GCEIS. Numerous locations of cultural importance were identified and assessed including important biological cultural resources, physical features and locations, and archaeological resources. Assessments were conducted by these tribes to identify potential impacts resulting from dam operations and to formulate possible treatment options. These studies were subsequently utilized by the BOR for the identification and evaluation of traditional cultural properties within the area of potential effect as defined by the PA program.

PA Program Work: Using the above resource inventories to establish baseline conditions, monitoring activities have been conducted to identify changes in resource conditions under the stipulations of the PA program. The NPS conducts monitoring throughout the year and produces annual monitoring reports for the Glen Canyon and Grand Canyon areas. Tribal groups conduct monitoring trips several times a year and assess changes to their traditional cultural resources and to assess the general health of the ecosystem through their own traditional value system.

Current monitoring activities conducted under the PA program include site visits, photographs, instrument mapping of sites, and remedial activities. Results of these monitoring activities indicate that physical and visitor-related impacts constitute the majority of impacts to the cultural resources. Based on the NPS FY 98 field work, two river corridor areas, Reaches 5 (RM 61.5-77.4) and 10 (RM 159.8-213.9), appear to have the highest frequencies of physical and visitor related impacts (Leap et. al. 1998).

Recommendations from monitoring efforts include a combination of preservation options (such as trail obliteration and retrailing, revegetation, and construction of checkdams to halt erosion) and recovery options (such as surface collection, mapping, testing, and data recovery) at features or sites (Leap et.al. 1998).

GCMRC Studies: Three on-going GCMRC projects will provide information that complements data collected under the PA program. This information includes a data synthesis of previously collected information under the PA program, mainstem flow and deposition modeling, and testing of a geomorphic erosional hypothesis. Compilation of existing data from a number of sources will identify data gaps in previously collected data. In addition, analysis currently underway will provide information on changes in site conditions over time. Empirical data has been collected for the projects addressing mainstem flow modeling and geomorphic hypothesis testing. Project data from the three efforts is expected in FY 2000.

Top of Page

1996 Test Flow Impacts on Cultural Resources

Many of the archaeological resources along the river corridor are contained in the sediment deposits which form the alluvial terraces. Since the completion of Glen Canyon Dam, the sediment resource has declined, and the alluvial terraces have eroded. A system-wide method for regenerating the river terraces and redistributing sediment is generally considered an essential component to maintaining integrity for cultural resources.

The 1996 Test Flow presented an opportunity to study the effects of high flow discharge from Glen Canyon Dam on alluvial terraces and margin deposits along the river corridor. The effects of these flows on the margin deposits and terraces is an important area of study since many of the terraces are of relatively recent origin and contain archaeological materials.

The 1996 Test Flow was expected to provide system-wide mitigation to most cultural sites in the Colorado River corridor through the accumulation of additional sediment. A positive effect was presumed but not guaranteed. As a result, some mitigation and monitoring of archaeological sites and other kinds of cultural resources, ethnobotanical resources, beaches, and sediment accumulation at the mouths of arroyos was undertaken to assess the results of the Flow. Terraces were studied in the Glen Canyon reach to determine whether terrace erosion occurred in this area as the loss of terrace deposits would impact the archaeological materials contained in the sediments.

The overall findings of the cultural resources studies done in conjunction with the 1996 Test Flow strongly suggest that the 45,000 cfs flow had either no effect, no adverse effect, or a beneficial effect on cultural resources. These findings support the original contention that habitat building flows can offer a system-wide mitigation for cultural resources. Some locations, especially in the Glen Canyon Reach, did experience loss of sediments or redeposition of sediments in a way that, in the long run, could be detrimental to cultural resources.

Top of Page

Cultural Resources Work In 1997 and 1998: Archaeological Sites

Archaeological site monitoring and management was conducted along the river corridor by the NPS (Leap et al. 1998). In Grand Canyon National Park (GCNP) and Glen Canyon National Recreation Area (GCNRA), monitoring was conducted at a total of 141 sites along the corridor and remedial activities were undertaken at 44 sites. The sites were selected based on protocols established under the Programmatic Agreement (PA) and the Historic Preservation Plan (HPP). Remedial activities at these sites included mapping, maintenance and construction or erosional controls such as check dams, and small data recovery (excavation) efforts.

Physical and visitor impacts were observed at many of the sites. Physical impacts are divided into eight categories that include surface erosion, gullying, arroyo cutting, bank slumpage, eolian/alluvial erosion or deposition, side canyon erosion, animal- caused erosion, and others. Impacts directly related to dam operations include bank slumpage, gullying and arroyo cutting in locations where drainage systems are actively changing to achieve the dam-induced, lowered river baselevel. At GCNP, eighty-one percent of the sites (N=80) monitored in FY 98 had some form of physical impact (Leap et. al. 1998:14). New physical impacts were observed at 49% of the sites (N=49). Surface erosion and gullying were the most commonly observed impact to archaeological sites. The highest frequency of impacts appears to occur at sites with structures/storage features, artifact scatters, and roasters/hearths, the most common archaeological sites encountered in the river corridor. The majority of the impacts appear to occur within the geomorphic river reaches 5 (Mile 61 to 76) and 10 (Mile 160 to 214).

Visitor impacts are separated into five categories that include trails, collection piles, on- site camping, criminal vandalism and other, undefined impacts. Trails are the most frequent impact 43% of the sites (N=43). Visitor impacts tend to occur at the same site types listed above for physical impacts. The majority of impacts appear to occur within River Reaches 4 (RM 35 to 61), 5 (RM 61.5-77.4) and 10 (RM 159.8-213.9) that have high site densities and popular river camps, where layovers with time for exploration above the beaches is possible.

In the GCNRA, active physical impacts are present at less than half of the 42 monitored sites with surface erosion the most frequent type at 29% (N=12) of the sites. Sites with river based drainages exhibited more active erosion than sites with terrace based drainages (Leap et. al.1998: 85-88). Visitor related impacts were evident at 45% (N=19) of the 42 sites monitored.

Mitigative measures were conducted at five sites under the direction of an Hopi Tribe archaeologist ( Yeatts 1998). The data recovery efforts were necessitated at erosional impacts to specific thermal features (roasters) and one cyst. Research questions were concerned with chronological issues, subsistence and subsistence technology, paleoenvironmental conditions and possibly seasonality of site use. Excavation, pollen, and flotation data provided information in the these areas. C-14 dates from datable charcoal indicate that the roasting features range in age from the Basket Maker III period ( AD 620 - 775), through Pueblo II (AD 970 - 1195) to modern use ( AD 1810- 1930), although the early dates may be somewhat problematic due to the possibility of reuse of older wood. Pollen and macrobotanical remains indicate that local and non-local woods were used as fuel, with mesquite being the dominant wood. Definitive data on the types of materials that were being processed in the roasting features was lacking, although there are remains of cactus, lily and Cheno-Am pollen in some samples. This work provides some information on prehistoric and historic activities from small mitigation efforts.

In the Spring 1998, additional remediation efforts occurred at Furance Flats. The report of the results of the excavation is currently being drafted. Quantitative information on archaeological resource baselines and resource changes for the period of 1991 through 1998 is currently being prepared for GCMRC. These data will be available at the end of FY 1999 and they will be included in next year's report.

Top of Page

Ethnobotanical Resources

Ethnobotanical resources were monitored by tribal groups during 1997 and 1998. These resources include specific plants and/or plants and plant locations that have importance to the groups based on their oral traditions. The Southern Paiute Consortium (SPC) monitored traditional resources to assess the condition of the resources relative to dam operations, to educate and train tribal members as monitors, to educate other tribal members and the general public, and to compile resource data bases (Austin et al. 1998).

Twelve locations were monitored by the SPC. The locations included traditional resources such as plants, rock art, and archaeological remains. The assessment of the tribal monitors is that the resources appear to be in good condition with the exceptions of visitor trails at two locations through archeological sites. Plant resources seem to be in very good conditions at three locations.

Hualapai ethnobotanical resources were monitored at five study sites along the river ( Phillips and Jackson 1997) during 1997. The trends that were noted during 1997 site visits included: 1) a reworking and erosion of unstable sediment deposits near the shore continued during 1997 resulting from the high water releases from GCD; 2) species and plant recovery following the 1996 test flow was reversed at some sites based on the high water releases from GCD, while vegetation away from the shoreline were less obvious; 3) at locations affected by high flows, two exotic species consistently increased in 1997, bermuda grass and camel thorn; and 4) the continual high water releases may erode sediments from the base of the root system of the Goodding Willow at Granite Park; and 5) the species diversity evident following the 1996 test flow may have been reversed with the continual high water releases in 1997. Recommendations where made to continue monitoring these locations to determine the health of these resources with the high water releases anticipated in 1998. The 1998 tribal monitoring report was not available at the time of this report draft.

The Hopi Tribe has initiated an ethnobotanical project to evaluate traditional plant resources. Some results from this project will be available next year.

Top of Page

Summary

Resource monitoring in 1997 and 1998 of archaeological and traditional resources suggests that archaeological resources continue to be impacted by physical impacts such as surface erosion and gullying in both the Grand and Glen Canyon areas. While some surface erosion is related to natural processes, sediment loss from erosional processes believed to be related to dam operations and mainstem water levels, and head cutting arroyos appear to impact archaeological sites at specific locations. Visitor impacts such as trailing, collection of artifacts have also been noted at archaeological sites and locations of traditional importance.

On-going studies conducted for GCMRC will provide information for subsequent reports. A data synthesis project is currently compiling baseline information to identify change in site conditions at archaeological monitoring locations. A stage flow and deposition modeling project will provide information on estimated sediment deposition at selected archaeological resource locations that can result from flow regimes associated with dam operations. An on-going geomorphic project is attempting to identify erosional processes that are related to dam operations versus naturally occurring processes. Results of these studies will be helpful in distinguishing resource impacts that are related to dam operations.

Assessment of ethnobotanical resources suggests somewhat mixed results. At some locations, the Southern Paiute Consortium have identified good conditions for traditional plant resources, while the Hualapai Tribe has expressed concerns for botanical resources at other locations and the increase in exotic plants such as Bermuda Grass and Camel Thorn. The results from the 1998 Hualapai monitoring season may provide additional information in this area.

Top of Page