Lake Lewis

{{Distinguish|Lewis Lake (disambiguation){{!}}Lewis Lake}}

{{Infobox body of water

| name = Lake Lewis

| image = Lake Lewis flood profiles.jpg

| caption = This figure shows four profiles of Lake Lewis at various flood levels. It illustrates that the lake back flooded several valleys in which the Touchet Beds were found.

| image_bathymetry =

| caption_bathymetry =

| coordinates = {{coord|46|10|N|119|00|W|format=dms|display=inline,title|type:adm1st_region:US-WA}}

| location = North America

| group =

| lake_type = Former lake

| inflow = Channeled Scablands

| outflow = Wallula Gap of the Columbia River

| catchment =

| basin_countries = United States

| length = {{convert|105|mi|km|abbr=on}}

| width = {{convert|130|mi|km|abbr=on}}

| area =

| depth =

| max-depth = {{convert|320|ft|m|0|abbr=on}}

| volume =

| residence_time = 20 incidents

| shore =

| elevation = {{convert|1200|ft|m|0|abbr=on}}

| islands =

| islands_category =

| cities =

| pushpin_map = Washington#USA

| pushpin_label_position =

| pushpin_map_alt = Location of Lake Lewis in Washington, USA.

| pushpin_map_caption =

| website =

| reference = Carson, Robert J.; Pogue, Kevin R. (1996). Flood Basalts and Glacier Floods:Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington. Washington State Department of Natural Resources (Washington Division of Geology and Earth Resources Information Circular 90). ISBN none.

}}

Lake Lewis was a large transient lake (lasting only days to weeks) in the Pacific Northwest region of North America, formed by periodic Missoula Floods along the Columbia River paleocourse between 21,000 and 16,000 years ago.{{cite journal |last1 = Last |first1 = G.V. |last2 = Rittenour |first2 = T.M. |year = 2021 |title = Chronology of Missoula Flood Deposits at the Coyote Canyon Mammoth Site. |journal = Quaternary |volume = 4 |issue = 3 |pages = 1–20, 5 |doi = 10.3390/quat4030020|pmid = |doi-access = free }}

Lake Lewis was formed when the restricted flow of watersFlow was restricted by a hydraulic dam—a restriction to the flow rate caused by a narrowed reach in a river valley. from periodic cataclysmic floods from Glacial Lake Missoula, pluvial Lake Bonneville, and perhaps from subglacial outbursts, backed up through the constriction formed by the Wallula Gap in the Horse Heaven Hills (southern Washington). Water also backed up further downstream on the Columbia River between Washington and Oregon, delaying the drainage of Lake Lewis. The water remained for a period of weeks before the flood waters drained through Wallula Gap, just southeast of the Tri-Cities area. Lake Lewis reached an elevation of about {{convert|1200|ft|m}} above sea level (today's sea level) before subsiding.{{Cite web |url=http://www.iceagefloodsinstitute.org/chapters/lakelewisinfo.html |title=Ice Age Floods Institute site on Lake Lewis |access-date=2006-10-01 |archive-date=2007-01-01 |archive-url=https://web.archive.org/web/20070101110203/http://www.iceagefloodsinstitute.org/chapters/lakelewisinfo.html |url-status=dead }}{{cite book|author=Bjornstad, Bruce|title=On the Trail of the Ice Age Floods: A Geological Guide to the Mid-Columbia Basin |publisher=Keokee Books; San Point, Idaho |year=2006|isbn=978-1-879628-27-4}}

Lake Lewis also flooded the Yakima, Walla Walla, Touchet and Tucannon river valleys.{{cite book|last1=Carson|first1=Robert J. |last2=Pogue|first2=Kevin R.|author-link2=Kevin Pogue|title=Flood Basalts and Glacier Floods:Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington |publisher=Washington State Department of Natural Resources (Washington Division of Geology and Earth Resources Information Circular 90)|year=1996|id=ISBN none}}