Little Lost River
{{Use American English|date=February 2025}}
{{Infobox river
| name = Little Lost River
| name_native =
| name_native_lang =
| name_other =
| name_etymology =
| image = LostRiverRangeID.jpg
| image_caption = The Little Lost River Valley viewed from the west slope of the Lemhi Range
| image_size = 300
| map = Lostidahomap.png
| map_size = 300
| map_caption = Map of the lost streams of Idaho including the Little Lost River
| pushpin_map =
| pushpin_map_size =
| pushpin_map_caption=
| subdivision_type1 = Country
| subdivision_name1 = United States
| subdivision_type2 = State
| subdivision_name2 = Idaho
| subdivision_type3 =
| subdivision_name3 =
| subdivision_type4 =
| subdivision_name4 =
| subdivision_type5 = City
| subdivision_name5 = Howe
| length = {{convert|49|mi|km|abbr=on}}, Northwest-southeast
| width_min =
| width_avg =
| width_max =
| depth_min =
| depth_avg =
| depth_max =
| discharge1_location=
| discharge1_min = {{convert|3|cuft/s|m3/s|abbr=on}}
| discharge1_avg = {{convert|64.1|cuft/s|m3/s|abbr=on}}{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/13118700.2009.pdf|title=USGS Gage #13118700 on the Big Lost River below Wet Creek, near Howe, ID|publisher=U.S. Geological Survey|work=National Water Information System|date=|accessdate=November 21, 2010}}
| discharge1_max = {{convert|509|cuft/s|m3/s|abbr=on}}
| source1 = Confluence of Sawmill and Summit Creeks
| source1_location = Upper Little Lost River Valley, Butte County
| source1_coordinates= {{coord|44|11|14|N|113|16|45|W|display=inline}}
| source1_elevation = {{convert|6100|ft|abbr=on}}
| mouth = Little Lost River Sinks
| mouth_location = Near Howe, Butte County
| mouth_coordinates = {{coord|43|45|52|N|112|58|22|W|display=inline,title}}{{GNIS|384886}}
| mouth_elevation = {{convert|4806|ft|abbr=on}}
| progression =
| river_system =
| tributaries_left = Sawmill Creek, Uncle Ike Creek
| tributaries_right = Summit Creek, Wet Creek
| custom_label =
| custom_data =
| extra =
}}
The Little Lost River is a river in the central part of the U.S. state of Idaho. It is approximately {{convert|49|mi}} longU.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. [http://viewer.nationalmap.gov/viewer/ The National Map] {{webarchive|url=https://web.archive.org/web/20120329155652/http://viewer.nationalmap.gov/viewer/|date=2012-03-29}}, accessed May 4, 2011 and drains an arid farming valley, the Little Lost River Valley, bordered by the Lost River Range on the west and Lemhi Range on the east. Instead of emptying into a larger body of water, it disappears into the ground at the edge of the Snake River Plain, a phenomenon that gives it its name. The water feeds into the Snake River Aquifer, eventually reaching the Snake River through a series of springs farther west.
Course
The river rises at the confluence of two similarly sized streams, Summit Creek and Sawmill Creek, {{convert|10|mi|km}} north of Hawley Mountain, in the middle of the Little Lost River Valley. The river flows generally south-southeast receiving many tributaries such as Wet (the largest), Badger, Deer, Uncle Ike, Sands, Cedarville, South, and Hurst creeks. Along its course the Little Lost is used for irrigation, but the only settlement of any size is Howe, situated near the mouth. A few miles past Howe, the river disappears into the earth at about {{convert|4806|ft|m}} above sea level.
The river drains about {{convert|963|mi2|km2}} of land entirely in Butte County. Its valley is about {{convert|50|mi|km}} long and {{convert|20|mi|km}} wide, with a floor width of {{convert|7|mi|km}}. Precipitation is generally very low and mostly in the form of snow.
Highway
The Little Lost River Highway is a north–south highway in Butte County that is {{convert|31.2|mi|km}} long and roughly parallels the lower Little Lost River. The road begins in the community of Howe, at an intersection with {{jct|state=ID|SH|33|noshield=yes}}, then runs roughly north-northwest towards the settlement of Clyde. Along the way, the highway crosses the Little Lost River twice. {{convert|3+1/2|mi|km|spell=In}} north of Clyde, the highway becomes Pahsimeroi Road.{{cite web|title=Overview of the Little Lost River Highway |url=https://www.google.com/maps/dir/44.1781761,-113.2833524/44.1357573,-113.2461907/43.7832794,-113.0046453/@43.9805587,-113.4240836,10z/am=t/data=!3m1!4b1!4m2!4m1!3e0?hl=en |website=Google Maps |publisher=Google, Inc. |accessdate=April 19, 2020}}