PALEONTOLOGICAL TECHNICAL MEMORANDUM FOR THE LAKE GREGORY DAM REHABILITATION PROJECT, SAN BERNARDINO COUNTY, CALIFORNIA Prepared for: Aspen Environmental Group 5020 Chesebro Road, Suite 200 Agoura Hills, CA 91301 Authors: Courtney Richards, Kim Scott and Sherri Gust Principal Investigator: Sherri Gust, Qualified Paleontologist October 2014 Revised June 2015 Cogstone Project Number: 2861 Type of Study: Paleontological resources assessment Sites: None USGS Quadrangle: San Bernardino North 7.5’, Silverwood Lake 7.5’ Area: 28.08 acres Key Words: Mesozoic plutonic rocks, Holocene alluvium, granite, diorite, low paleontological sensitivity 1518 West Taft Avenue Branch Offices cogstone.com Orange, CA 92865 San Diego – Riverside – Morro Bay - Sacramento Toll free (888) 333-3212 Office (714) 974-8300 Federal Certifications 8(a), SDB, 8(m) WOSB State Certifications DBE, WBE, SBE, UDBE Lake Gregory Dam Paleontology Memorandum TABLE OF CONTENTS EXECUTIVE SUMMARY ........................................................................................................ III INTRODUCTION......................................................................................................................... 1 PURPOSE OF STUDY ........................................................................................................................... 1 PROJECT DESCRIPTION AND LOCATION ................................................................................... 2 PROJECT PERSONNEL ....................................................................................................................... 4 BACKGROUND ........................................................................................................................... 5 GEOLOGICAL SETTING .................................................................................................................... 5 STRATIGRAPHY .................................................................................................................................. 5 MESOZOIC PLUTONIC ROCKS ............................................................................................................. 5 HOLOCENE ALLUVIAL SEDIMENTS ..................................................................................................... 5 RECORD SEARCHES ................................................................................................................. 7 PALEONTOLOGICAL SENSITIVITY .................................................................................... 7 CONCLUSIONS AND RECOMMENDATIONS ...................................................................... 8 REFERENCES CITED ................................................................................................................ 9 APPENDIX A. PALEONTOLOGICAL RECORDS SEARCH ............................................ 10 APPENDIX B. PFYC CRITERIA............................................................................................ 13 LIST OF FIGURES FIGURE 1. PROJECT VICINITY........................................................................................................... 1 FIGURE 2. PROJECT AREA ................................................................................................................ 3 FIGURE 3. GEOLOGY OF PROJECT AREA ........................................................................................... 6 LIST OF TABLES TABLE 1. PALEONTOLOGICAL SENSITIVITY RANKINGS ................................................................................ 8 ii Lake Gregory Dam Paleontology Memorandum EXECUTIVE SUMMARY The purpose of this study was to identify any possible paleontological resources that could be present in the Lake Gregory Dam Rehabilitation project area located in San Bernardino County, California. This study was requested by San Bernardino County to meet their responsibility as the lead agency under the California Environmental Quality Act (CEQA). The proposed Lake Gregory Dam Rehabilitation Project consists of structural reinforcements to the existing dam. Four alternatives for remediation of the dam are under consideration: downstream stabilization buttress, cement deep soil mixing, stone column, and upstream asphalt facing alternatives. The downstream stabilization buttress is the preferred and State Division of Safety of Dams (DSOD) approved alternative. The surface of the Project Area, including the borrow sites added in 2015, is mapped almost entirely as Mesozoic plutonic rocks. A small portion of Lake Gregory is mapped as Holocene alluvial sediments. Paleontological records searches of the Lake Gregory were conducted at the San Bernardino County Museum and in online databases and literature. All searches were negative for fossils within the Project. Further, it was determined that the geologic units of the Project area do not have potential for paleontological resources. Mesozoic plutonic rocks were ranked very low or PFYC 1 as they do not contain fossils due to the way they form. The Holocene alluvial sediments were ranked low or PFYC 2. Due to its young age, it is not sensitive for fossil resources. Neither the record searches nor background research indicate any sediments sensitive for paleontological resources will be impacted by the proposed Project. No further paleontological work is required. If unanticipated fossils are unearthed during construction, work should be halted in the immediate vicinity of the find until it can be evaluated by a qualified paleontologist. iii Lake Gregory Dam Paleontology Memorandum INTRODUCTION PURPOSE OF STUDY The purpose of this study was to identify any possible paleontological resources that could be present in the Lake Gregory Dam Rehabilitation project area located in San Bernardino County, California (Figure 1). This study was requested by San Bernardino County to meet their responsibility as the lead agency under the California Environmental Quality Act (CEQA). Figure 1. Project vicinity 1 Lake Gregory Dam Paleontology Memorandum PROJECT DESCRIPTION AND LOCATION The proposed Lake Gregory Dam Rehabilitation Project consists of structural reinforcements to the exiting dam. Four alternatives for remediation of the dam are under consideration: downstream stabilization buttress, cement deep soil mixing, stone column, and upstream asphalt facing alternatives as well as additional project elements. The downstream stabilization buttress is the preferred and State Division of Safety of Dams (DSOD) approved alternative. It would include construction of an earthen buttress with a drainage system and slope protection. The Project would also involve removal of existing foundation material at the base of the dam; tree and vegetation removal; and hauling and processing of earthen material from existing stockpiles of previously dredged material from Lake Gregory and Lake Arrowhead. The cement deep soil mixing (CDSM) alternative would consist of injecting CDSM to form columns that would provide stiffness and reduce liquefaction potential. Columns would be placed in a grid pattern across the embankment. The stone column alternative would consist of construction of a series of columns arranged in three rows across the embankment to provide stiffness. The upstream asphalt alternative involves construction of a firm, semi permeable asphalt slope upstream of the dam. Additional soil will come from 3 acres of borrow sites (Ponderosa 1 and 2) and waste material will be stockpiled at the existing Thousand Pines Stockpile site (Figure 2). Lake Gregory is located in the San Bernardino Mountains approximately 14 miles north of the City of San Bernardino in the community of Crestline. Specifically, the Lake Gregory Dam is mapped on Section 23 of Township 2 North, Range 4 West of the San Bernardino North, USGS 7.5’ quadrangle in the San Bernardino Base and Meridian. The haul road is located on the San Bernardino North and Silverwood Lake USGS 7.5’ quadrangles on Sections 14, 22, and 23 of Township 2 North, Range West. 2 Lake Gregory Dam Paleontology Memorandum Figure 2. Project area 3 Lake Gregory Dam Paleontology Memorandum PROJECT PERSONNEL Cogstone Resource Management Inc. (Cogstone) conducted the paleontological resources studies. Sherri Gust, a Qualified Paleontologist, served as the Principal Investigator for the project, supervised all work, wrote the conclusions and recommendations, and edited this report. She has a M.S. in Anatomy (Evolutionary Morphology) from the University of Southern California, a B.S. in Anthropology from the University of California at Davis and over 35 years of experience in California. Courtney Richards prepared sections of the report. Richards has an M.S. in Biological Sciences with an emphasis in Paleontology from Marshall University. Kim Scott updated this report for the new borrow areas in 2015. Ms. Scott has a M.S. in Biology with an emphasis in Paleontology from California State University, San Bernardino, a B.S. in Geology with an emphasis in Paleontology from University of California, Los Angeles and over 20 years of experience in California geology and paleontology. André Simmons prepared the GIS maps throughout this report. Simmons has a M. A. in Anthropology specializing in Anthropological Archaeology from California State University, Fullerton, a B.A. in Anthropology also from CSUF, cross-training in paleontology, and more than four years of GIS experience with certification. Lindsay Porras performed the cultural and paleontological resources field survey. Ms. Porras holds a B.A. in Anthropology from