GEOLOGIC RECONNAISSANCE MAPPING OF LAKE SHANNON AND BAKER LAKE SHORELINES, SKAGIT AND WHATCOM COUNTIES, WASHINGTON

Geologic reconnaissance mapping of the Baker Lake and Lake Shannon reservoir shorelines was performed in Spring 2001 as part of a reservoir shoreline erosion and deposition study conducted for re-licensing of the Upper and Lower Baker River Hydroelectric Projects. Baker Lake shoreline mapping occurred during very low pool levels of about elevation 683 to 689 feet. Lake Shannon shoreline mapping occurred during a filling period with pool levels of about elevation 422 to 425 feet. Mapping was conducted via foot where possible and where the shoreline/reservoir interface was too steep to permit survey by foot, mapping was conducted via boat. An extensive photographic database was developed to document baseline erosion and deposition conditions along the shorelines and within the drawdown zones of Lake Shannon and Baker Lake. Stratigraphic units identified along the shorelines of Lake Shannon include outwash, till, glaciolacustrine deposits, and undifferentiated bedrock. Stratigraphic units identified along Baker Lake shorelines include older alluvium including lahar deposits, outwash, till, glaciolacustrine deposits, and undifferentiated bedrock.