Survey Data Collection for the Bureau of Reclamation at Glen Canyon Dam near Page, Arizona, November 2020.

This dataset describes survey data collected for the Bureau of Reclamation (Reclamation), the agency in charge of regulating Colorado River water control operations impounding the Lake Powell reservoir. Additional intent of the collected data was to assure consistencies among gaging elevations at Glen Canyon Dam near Page, Arizona as well as verification and alignment of a recently published topobathymetric digital elevation model for Lake Powell. Glen Canyon Dam is a concrete arch-gravity dam on the Colorado River in northern Arizona and is the second largest man-made reservoir in the United States. The location was chosen to survey due to uncertainty in the local datum used by the Reclamation as well as uncertainties regarding elevation consistencies among the local United States Geological Survey (USGS) gaging operation 09379900 Lake Powell at Glen Canyon Dam, Arizona. The primary component of the survey involved a differential leveling campaign derived from fiducial benchmarks used to perpetuate elevation to a variety of objective points. Additionally, the survey consisted of a Global Navigation Satellite System (GNSS) (Rydlund and Densmore, 2012) campaign constrained to fiducial benchmarks that were used to develop network solutions at the same objective points derived by leveling. This Level I static network GNSS campaign was conducted to quality assure the leveling campaign as well as integrate ellipsoid and geoid height characteristics tied to active monumentation. A third GNSS campaign involved a level III single-base static survey of Lake Powell water-surface elevations that were conducted at marina locations of Antelope and Wahweap, Arizona, along with a location at Bullfrog, Utah to provide comparison and assure alignment of the topobathymetric digital elevation model used to develop a current area capacity table at Lake Powell. Six items containing the survey data and the relevant information are available for download. They are GCD_USBR_LEVEL_SUMMARY.csv, GCD_USBR_LEVEL_SUMMARY.zip, GCD_USBR_MARK_RECOVERY.zip, GCD_USBR_STATIC_NETWORK.csv, GCD_USBR_WSE.csv, and GCD_USBR_LAKE_SURVEY.zip. Differential leveling final elevation for selected objective points are located in GCD_USBR_LEVEL_SUMMARY.csv. Field notes and details representing fiducial benchmarks and objective points within the differential leveling campaign are located in GCD_USBR_LEVEL_SUMMARY.zip. Fiducial marks recovery photographs and integration of USGS recovery forms are located in GCD_USBR_MARK_RECOVERY.zip. GNSS survey solutions referenced in Arizona State Plane Central Zone 0202, Universal Transverse Mercator 12 North, and Geographic (Decimal Degrees) are located in GCD_USBR_STATIC_NETWORK.csv. Orthometric heights in both Geoid 18 and Geoid 12b along with comparisons to differential leveling surveys are also located in GCD_USBR_STATIC_NETWORK.csv. The Lake Powell survey solutions are in the same format as GCD_USBR_STATIC_NETWORK.csv but located in GCD_USBR_WSE.csv. Photographs and USGS GNSS Level IV static observation forms of the lake survey are located in GCD_USBR_LAKE_SURVEY.zip. References Cited: Rydlund, P.H., Jr., and Densmore, B.K., 2012, Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to establish vertical datum in the United States Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p. with appendixes., https://doi.org/10.3133/tm11D1.