UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY HYDROLOGIC RECONNAISSANCE OF THE CHILKAT RIVER BASIN, SOUTHEAST ALASKA With Special Reference to the Bald Eagle Critical Habitat at the Tsirku River A.lluvia1 Fan By Edward F. Bugliosi U.S. GEOLOGICAL SURVEY Open-File Report 84-618 Prepared in cooperation with the ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGICAL AND GEOPHYSICAL SURVNS Anchorage, Alaska 1985 UNITED STATES DEPARTMENT OF THE INTERIOR WILLIAM P, CLARK, SECRETARY GEOLOGICAL SURVEY Dallas L. Peck, Director Far additional information Copies of this report can write to: be purchased from: District Chief Open-File Services Section U.S. Geological Survey Western Distribution Branch Water Resources Division U.S. Geological Survey 4230 University Drive, Suite 201 Box 25425, Federal Center Anchorage, Alaska 99508-4664 Denver, Colorado 80225 (907) 271-4138 (303) 234-5888 CONTENTS Page Abstract ............................................................... Introduction........................................................... Acknowledgments ......,,,..................................e..0.... Physiography ...................................................... Climate ........................................................... Geology ................................................................ Geomorphic and glacial history.. ....................................... surface water . ............................................... Chilkat I ................................................... Streamflow ........................................................ Cheutical quality ............................................. Sus~)ended sediment ........................................ ... Ground water. ................................................................ Ts:lrku Ibiver alluvial fan .............................................. G1;jcial history ................................................... Fa1n sedimentology and morphology .................................. Tsirku alluvial fan aquifer ............................................ Discharge areas ................................................... Recharge areas .................................................... Tsirku alluvial fan water budget .................................. Heat-flow calculations ................................................. Summary and conclusions.... ............................................ References cited ....................................................... ILLUSTRATIONS igure 1 . Map showing location of study area ........................... 2 . Map of Chilkat River basin. major subbasins. and locations mentioned in text ............................................ 3. Graph showing cor nparisam of mean monthly values of pre- cipitation and tt .ure for Haines and Klukwan. 1927-1943 . 4. Map of surficial................................................... geology of Tsirku alluvial fan area near geologic section of Tsirku alluvial fan area near K. ................................................... 6. Bathmetric map and water-quality sampling sites at Chilkat Lake! near IUukwan............................................ 7. Gra~~hs sha wing temperature. specific conductance. pH. and dissvlveu-oxygen. I... 3 profiles at Chilkat Lake .................... B . Diagrams showing percentage composition of major cations and anions. and dissolved-solids concentration for Chilkat Lake CLLLU-*a its outlet stream ........................................ 9 . Map g contiinuous-record gaging station and miscella- neou uremenlL sites in the Chilkat River basin ........... n tt-2- 1b . nyurugLayu for KLehini River. October 1981 to September 1982 . 1 . Graph showing d ischarge relationship between KZehini and Tsirku Riv ers .. ILLUSTRATIONS--Continued Page 12. Map showing losses and gains in streamflow in the Tsirku River alluvial fan area, April 6, 1982........,,.........,... 13. Map of surface-water-quality sites in Chilkat River basin, percentage of major cations and anions, and total hardness... 14. Graph showing suspended-sediment discharge versus stream discharge for Chilkat, Klehini, and Tsirku Rivers at high- and low-flow periods ......................................... 15. Cross section across Chilkat Valley and Tsirku fan showing bedrock depth from seismic refraction and gravimetric data... 16. Map showing ground-water-quality sites on and near the Tsirku alluvial fan, percentage of major cations and anions, and total hardnes~................,,............,,...~.........~. 17. Map of Tsirku alluvial fan and vicinity, locations of observation wells and hydrogren-oxygen isotope sampling sites................ ..,,.....,...........*,...........*...* . 18. Photograph of Tsirku alluvial fan, October 5, 1981..,,,,,,... 19. Hydrograph of observation wells AR-3 and AR-4 at the toe of the Tsirku alluvial fan showfng relation between potentiome- tric surface in deep and shallow ground-water systems..,..,.. 20. Hydrograph of observation wells AR-1, AR-2, and AR-7 on Tsirku alluvial fan showing the relationship between wells at the head, middle, and toe of fan..................,,.*,.w. 21. Potentiometric surface maps of shallow ground-water systems and direction of ground-water movement, Tsirku alluvial fan: a. March 11-16, 1983..........,,,,,,,....,................... b. May 11, 1983....,............................,.. .......... 22. Photograph of part of toe of Tsirku alluvial fan, and Chilkat River on March 23, 1982.....,.,.,,................... 23. Photograph of Tsirku alluvial fan, March 22, 1982.........,.. 24. Photograph of Tsirku alluvial fan, June 6, 1981............., 25. Block diagram of Tsirku River alluvial fan and vicinity, showing elements of the water budget for the period October 1982 through May 1983............... ......................... TABLES Table 1. Percentage ice cover in the major subbasins within the Chilkat River basin.......................................... 9 2. Surface-water quality data for selected sites in the Chilkat River basin.................................................. 12 3. Drainage area, period of record, and maximum and minimum discharge for selected streams measured in the Chilkat River - basin.............................................,*,....,... 17 4. Monthly mean flow for Hlehini and Tsirku rivers, 1982 water Page i. Ground-water quality data for four observation wells in the Chilkat River basin.... ......,....,....,...g....,............ 2 7 I. Oxygen and hydrogren isotope'data from samples collected at ~rface-watersites and observation wells.....,...., 38 CONVERSION TABLE to obtain ~ch(in millimeter (mm) lot (ftl meter (m) mile (mi) kilometer (km) square mile (mi2 square kilometer (km2 ) cubic foot (ft9: cubic meter (ms ) acre-f oo e-f t cubic meter (m' ) faot per (ft/mi> meter per kilometer (m/km) square f r day (ft2/d) square meter per day (m2 Id) cubic foot per second (ft' 1s) cubic meter per second (mS /s) ton, short, per day Cton/d) 0.9072 megagram per day (~g/d) degree Fahrenheit (OF) "~=5/9(OF-32) degree Celsius (OC) micrornho per centimeter at 25°C microsiemens per centimeter (pmholcrn at 25' C) 1.0000 at 25°C (p~/cmat 25' C) tions in this report are: -,,L, milligram- per liter J.I~/L, mil crogranI per liter NTU, neph~elometl :ic turbidity unit HYDROLOGIC RECONNAISSANCE OF THE CHILKAT RIVER BASIN, SOUTHEAST USKA With Special Reference to the Bald Eagle Critical Habitat at the Tsirku River Alluvial Fan - - By Edward F, Bugliosi ABSTRACT The Chilkat River basin in southeast Alaska is characterized by rugged, highly dis- sected mountains with steep-gradient streams, braided rivers in broad alluvium- filled valleys, and numerous glaciers. A wide seasonal range in temperature and strong orographic effects cause variations in the amount and distribution of pre- cipitation, and thus in the resulting runoff and streamflow. Streamflow is lowest in winter, when precipitation at higher altitudes is stored as snow, and greatest in summer, when melting snow and glacier ice augment flow. Ground-water seeps and springs flowing from alluvial fans contribute to streamflow year round. A groundwater discharge zone of particular interest is that along the toe of the Tsirku River alluvial fan, 20 miles north of Haines. During winter, the relatively warm (4 to 6 degrees Celsius) ground water maintains open leads in a reach of the Chilkat River downstream from the fan. This ice-free reach provides favorable spawning habitat for a late run of chum and coho (silver) salmon, which in turn attracts the world's largest concentration of bald eagles (more than 3,000 birds). The principal source of recharge to the ground-water system in the fan is loss of water through the beds of the many distributary channels across the fan surface. Calculation of a water budget for the system for the period October 1982 through May 1983 indicates that groundwater discharge at the toe of the fan averages 640 cubic feet per second. Surface and ground waters are chemically similar, calcium bicarbonate types. All stream samples had dissolved-solids concentrations of less than 115 milligrams per liter; values for ground water were slightly greater. During high summer flows, the suspended-sediment concentrations of the glacially fed Chilkat, Tsirku, and Klehini Rivers ranged from 361 to 1,530 milligrams per liter (6,360 to 22,300 tons per day). INTRODUCTION The Chilkat River basin, at the head of Lynn Canal about 80 mi northwest of Juneau in southeast Alaska (fig. 11, is bordered by the Takhinsha Mountains