THE 1979-1980 GEOTHERMAL RESOURCE ASSESSMENT PROGRAM IN WASHINGTON by Michael A. Korosec and J. Eric Schuster, with contributions from David D. Blackwell, Z. Frank Danes, and Geoffrey A. Clayton Washington State Department of Natural Resources Division of Geology and Earth Resources Olympia, Washington 98504 Open File Report 81-3 1980 Prepared Under U.S. Department of Energy Contract No. DE-AC03-79ET27014 CONTENTS Page I. Introduction Temperature-gradient and heat-flow investigations Geochemistry of thermal and mineral springs Geologic mapping Resistivity Gravity Geothermal resource maps II. Geothermal Project Publications References Cited III. Heat flow and geothermal gradient measurements in Washington through 1979 by David D. Blackwell Introduction Data format Discussion References cited8 Additions and comments: by Michael A. Korosec IV. Thermal and mineral spring investigations, 1978-1979 (surveys and analyses) by Michael A. Korosec Methods Results Individual spring system investigations Baker Hot Springs Geothermal features Geology Comments Bonneville Hot Springs-Moffett's Hot Springs 60 Geothermal features Page Individual spring system investigations-Continued Bonneville Hot Springs-Continued Geology Comments Collins Hot Springs Geothermal features4 Geology Comments Goose Egg Soda Spring Geothermal features Geology Comments Lester Hot Springs Geothermal features Geology Comments Longmire Mineral Springs Geothermal features Geology Comments Reference Medicine Creek Mineral Spring Geothermal features Geology Comments Reference Page Individual spring system investigations-Continued Ohanapecosh Hot Springs Geothermal features Geology Comments Orr Creek Warm Springs Geothermal features Geology Comments Sol Duc Hot Springs Geothermal features Geology Comments Sulphur Creek Hot Springs Geothermal features Geology Comments Reference Summit Creek Soda Spring Geothermal features Geology Comments V. Regional gravity survey of the southern Cascades, Washington by Z. F. Danes Introduction Research Additions and Comments: by Michael A. Korosec Page VI. Geology of the White Pass-Tumac Mountain area, Washington by Geoffrey A. Clayton Abstract Introduction: the structure and stratigraphy of the Tertiary rocks in the Carlton Pass-White Pass-Rimrock Lake-Goat Rocks region Previous work Objectives and problems Quaternary volcanic rocks in the Tumac Mountain-White Pass- Goat Rocks area Results References cited Additions and comments: by Michael A. Korosec VII. Geothermal investigations in the Camas area, Washington, 1979 by Michael A. Korosec and J. Eric Schuster Introduction The 1979 project Results Discussion Conclusions VIII. Geothermal assessment of Mount St. Helens, Washington, 1979 by Michael A. Korosec and J. Eric Schuster Introduction Results Discussion Conclusions IX. Bibliography of Geothermal Resource Information for the State of Washington by Michael A. Korosec Page Appendix A — Well temperature information and locations in the State of Washington by Michael A. Korosec Appendix b — Geology of White Pass-Tumac Mountain Area, Washington by Geoffrey Clayton Appendix C — Resistivity study of Camas, Washington: Final Report by F. A. Rigby and R. B. McEuen Appendix D — Temperature versus depth logs for all available wells in Washington by D. D. Blackwell Note: Appendix D is part of special edition reports only. This section is available from the Division of Geology and Earth Resources as Open File Report 80-9. List of Tables Page 3.1 Pre-1979 Geothermal Gradients and Heat Flow in Washington State 3.2 Washington - Heat Flow (Pre-1979) 3.3 1979 Geothermal Gradients and Heat Flow in Washington State 3.4 Results of Heat Flow Drilling, 1979, Southwest Cascades, Washington 4.1 Thermal and Mineral Springs of Washington State 4.2 Thermal and Mineral Spring Chemistry (DGER) 4.3 Thermal and Mineral Spring Chemistry (Battelle) 4.4 Water Identifier Codes 4.5 Thermal and Mineral Spring Data List of Figures 3.1 Heat Flow and Temperature Gradient Map of Washington (Pre-1979 Data) 3.2 Preliminary Heat Flow Region Map of Washington 3.3 Anomalous Temperature Gradient areas of Washington 3.4 Preliminary Heat Flow Map of Southwestern Washington 8.1 Temperature vs Depth Profile for Mount St. Helens Drill Holes 8.2 Earthquake hypocenters near Mount St. Helens from 1971 through 1978 I. INTRODUCTION Geothermal resource assessment activities during 1979 have included temperature- gradient and heat-flow investigations, geochemical investigation of mineral and ther- mal springs, geologic mapping, a resistivity survey, regional gravity measurements, and preparation of geothermal resource maps for Washington. The State of Washington thus far has received very little attention from prospec- tive geothermal developers. Consequently, the geologic, geochemical, and geophysical data base with respect to geothermal has been either scattered or nonexistent. Our assessment efforts have, therefore, been primarily directed toward synthesizing and interpreting existing data, and providing regional geophysical and geochemical data bases where none have previously existed. Attention was focused on the southwestern Cascades of Washington during 1979. The work was carried out by both subcontractors and in-house geologists. The findings of each of the project investigators working on the geothermal assessment program are presented as separate chapters in this report. Some of the individual projects are more complete than others and therefore appear as more detailed presentations. At the end of each chapter report, the principle investigators, J. Eric Schuster and Michael A. Korosec, have added further information, including comments on project status, how it relates to other projects, usefulness, work yet to be completed, future directions, and interpretations of the data. The interpretations are occasionally made with little data or background information and may not repre- sent the beliefs of the project Investigator, but are presented anyway so as to help shape future investigations in the areas affected. Temperature-Gradient and Heat-Flow Investigations Shallow drilling and measurements of temperature gradients in existing wells were accomplished in the following areas: (1) the Cowlitz River valley between Interstate 5 on the west and White Pass on the east, (2) the Mount St. Helens area, and (3) the Camas area, located in Clark County east of Vancouver, Washington. In the Cowlitz River valley, usable temperature gradients were measured in about 22 water wells located in the western portion of the valley, generally between Interstate 5 on the west and the City of Morton on the east. Temperature gradients in these wells are generally 30°C/km or less. Two gradients measured in existing wells located to the east of the City of Morton and gradients measured in five of the six 500-foot-deep gradient wells drilled during 1979 between the town of Randle and White Pass (both to the east from Morton) are 46°C/km and higher. This suggests that the transition between "Puget Lowland type" temperature gradients of about 30-40°C/km or less (with associated heat flow values of less than 40 mWatts/m2) and "High Cascade type" gradients of about 45°C/km or more (with associated heat flow values of 60 to 80 mWatts/m2 or higher) occurs between the City of Morton and the town of Randle. The transition appears to be fairly sharp (perhaps 8 kilometers or less in width) and seems to occur closer to Morton than to Randle. In the Mount St. Helens area, there are no existing wells except for three holes drilled during 1979 by the Division. The temperature gradient from St. Helens No. 1 drill hole, to the north-northwest of Mount St. Helens, is very low at 19°C/km, and appears to be affected by local hydrologic conditions. In St. Helens No. 2 drill hole, to the west of Mount St. Helens, the gradient is 38°C/km. The third drill hole, to the east-southeast of Mount St. Helens, is isothermal. In the Camas area, several gradients measured in existing water wells located to the west of 122°20'W. (about the longitude of the City of Camas) yielded temperature gradients of less than 40°C/km, but two water wells located to the east of 122°10'W. produced gradients of about 53° and 69°C/km. Two gradient wells drilled by the Division near Camas produced gradients of 31.5°C/km and 37°C/km. The former well was drilled in Tertiary volcanics and sediments and the latter entirely in late(?) Tertiary sediments. All heat flow values calculated for the Camas area fall in the range of 40 to 60 mWatts/m2. Geochemistry of Thermal and Mineral Springs During the 1979 field season, 46 springs, representing 15 different spring systems located in the Cascade and Olympic Mountains, were surveyed for temperature, flow, conductivity, and pH. Of these springs, 38 were sampled and analyzed by the Division of Geology and Earth Resources. Chemical species measured include specific conductivity, pH, Na, K, Ca, Mg, Li, SiO2, alkalinity, Cl, CO2, Br, and I. Tables 4.1 through 4.5 present a listing of the springs, their temperatures, specific conductivities, and reservoir temperatures as predicted by the SiO2-Quartz and Na-K-Ca geothermometers. Detailed descriptions, analyses, and discussions of observed chemistry for these springs are presented in Chapter IV. Geologic Mapping Geoff Clayton, from the University of Washington, mapped the volcanic geology of the Tumac Mountain-White Pass area, located to the south and east of Mount Rainier National Park. Field studies have been completed and a geologic map has been prepared. Resistivity A resistivity study was conducted in the Camas area by F. A. Rigby of Science Applications, Inc., and R. B. McEuen of Exploration Geothermics. Two regions of relatively low resistivity were found, and drill sites were recommended to test these two areas. The two Camas drill holes were located at or within a short distance of the drill sites recommended by Rigby and McEuen. Gravity During 1979, Z. F. Danes of the University of Puget Sound measured gravity at 743 stations in the south Cascades. The area covered extends from 121°W. on the east to 122°30'W. on the west, and from the Columbia River on the south to the Cowlitz River valley on the north.