WATERSHED ASSESSMENT WATER RESOURCE INVENTORY AREA 28, SALMON-WASHOUGAL Linton Wildrick, Tom Culhane, Don Davidson, and Kirk Sinclair Open-File Technical Report 98-02 Washington Department of Ecology Southwest Regional Office Water Resources Program The Department of Ecology is an equal opportunity agency and does not discriminate on the basis of race, creed, color, disability, age, religion, national origin, sex, marital status, disabled veteran’s status, Vietnam Era veteran’s status, or sexual orientation. If you have special accommodation needs or require this document in alternative format, please contact Paula Smith at (360) 407-6607 (Voice) or (360) 407-6006 (TDD). Table of Contents ACKNOWLEDGMENTS ........................................................................................................................................... vi ABSTRACT................................................................................................................................................................ vii INTRODUCTION ........................................................................................................................................................ 1 WATER-RESOURCES MANAGEMENT IN WASHINGTON ............................................................................ 1 SCOPE OF REPORT............................................................................................................................................... 1 WATERSHED DESCRIPTION ................................................................................................................................... 2 PHYSICAL GEOGRAPHY and GENERAL TOPOGRAPHY............................................................................... 2 HYDROGRAPHY ................................................................................................................................................... 2 LAND COVER ........................................................................................................................................................ 3 LAND USE .............................................................................................................................................................. 3 POPULATION GROWTH ...................................................................................................................................... 3 WATER DEMAND...................................................................................................................................................... 5 WATER RIGHTS .................................................................................................................................................... 5 WATER-RIGHTS QUANTITIES FOR VARIOUS USES ..................................................................................... 5 APPLICATIONS FOR NEW WATER RIGHTS .................................................................................................... 6 ESTIMATES OF ACTUAL GROUND-WATER USE........................................................................................... 8 WATER-RIGHT CLAIMS ...................................................................................................................................... 8 RELATIONSHIP BETWEEN WATER RIGHTS AND WATER-RIGHT CLAIMS........................................... 10 SURFACE-WATER SOURCE LIMITATIONS................................................................................................... 10 RESERVATION OF FUTURE PUBLIC WATER SUPPLY................................................................................ 10 HYDROLOGY ........................................................................................................................................................... 12 THE WATER CYCLE........................................................................................................................................... 12 CLIMATE ......................................................................................................................................................... 13 PRECIPITATION ............................................................................................................................................. 13 PRECIPITATION TRENDS............................................................................................................................. 13 THE SOIL-WATER BALANCE: EVAPOTRANSPIRATION AND DEEP PERCOLATION ...................... 14 HYDROGEOLOGY .............................................................................................................................................. 15 GEOLOGIC SETTING..................................................................................................................................... 15 HYDROGEOLOGIC UNITS AND WELL YIELDS ....................................................................................... 16 GROUND-WATER RECHARGE .................................................................................................................... 17 GROUND-WATER MOVEMENT AND DISCHARGE ................................................................................. 18 SEEPAGE TO STREAMS................................................................................................................................ 19 SPRINGS........................................................................................................................................................... 21 GROUND-WATER WITHDRAWALS ........................................................................................................... 22 GROUND-WATER CONDITIONS...................................................................................................................... 22 EFFECTS OF GROUND-WATER WITHDRAWALS.................................................................................... 22 URBAN CONSTRUCTION ............................................................................................................................. 24 CHANGES IN GROUND-WATER LEVELS AND STORAGE..................................................................... 24 REDUCED GROUND-WATER DISCHARGE TO STREAMS AND RIVERS............................................. 25 REDUCED GROUND-WATER DISCHARGE TO SPRINGS ....................................................................... 25 EFFECTS OF ADDITIONAL GROUND-WATER WITHDRAWALS .......................................................... 25 SURFACE WATERS AND STREAMFLOW....................................................................................................... 27 FACTORS AFFECTING SURFACE WATERS.............................................................................................. 27 DATA SOURCES AND GAGING HISTORY.................................................................................................27 ANNUAL RUNOFF ......................................................................................................................................... 28 SEASONAL PATTERNS AND ANNUAL TRENDS ..................................................................................... 30 LOW FLOWS COMPARED TO WATER-YEAR PRECIPITATION ............................................................ 31 ANNUAL FLOWS COMPARED TO WATER-YEAR PRECIPITATION .................................................... 31 i WATER QUALITY.................................................................................................................................................... 33 QUALITY OF SURFACE WATERS.................................................................................................................... 33 QUALITY OF GROUND WATERS..................................................................................................................... 35 FISH STOCKS AND HABITAT................................................................................................................................ 37 ALTERATIONS TO HABITAT............................................................................................................................ 37 SALMON DISTRIBUTION, ABUNDANCE, and STOCK STATUS ................................................................. 38 LOWER COLUMBIA STEELHEAD CONSERVATION INITIATIVE ............................................................. 39 SUMMARY OF FINDINGS ...................................................................................................................................... 40 HYDROGEOLOGY .............................................................................................................................................. 40 CLIMATE.............................................................................................................................................................. 40 EFFECTS OF GROUND-WATER USE ON THE HYDROLOGIC SYSTEM.................................................... 41 WATER DEMAND ............................................................................................................................................... 41 FISH STOCKS....................................................................................................................................................... 42 WATER QUALITY............................................................................................................................................... 43 CONCLUSIONS........................................................................................................................................................