Little Lost River Subbasin
Subbasin at a Glance
|Hydrologic Unit Code||17040217|
|Size||963 square miles (616,320 acres)|
Water Bodies with EPA-Approved TMDLs (Category 4a)
Little Lost River, Main Fork, Sawmill Creek, Wet Creek
|Beneficial Uses Affected||Cold water aquatic life, salmonid spawning|
|Major Land Uses||Forestry, agriculture|
|Date Approved by EPA||September 2000
EPA Approval Letter
|Date 2015 Temperature Addendum Approved by EPA||January 2016
EPA Approval Letter
The Little Lost River subbasin is located in eastern Idaho on the northern margin of the Snake River plain. The subbasin is approximately 50 miles long by 20 miles wide (963 square miles). The valley floor averages 7 miles wide and is fairly consistent in width from the head of the valley to the mouth. Shaped like a long rectangle, the high-elevation valley is flanked by the Lost River Range to the west and the Lemhi Range to the east.
2000 Subbasin Assessment and TMDL
Water quality, native fish populations, and riparian habitat conditions have been issues of concern in the Little Lost River subbasin since the combined effects of flooding, wildfires, warm season grazing, exotic species, and human-made diversions have combined to alter sediment deposition, fish populations, and riparian vegetation along the listed segments.
The listed segments are also important components of the Little Lost River Bull Trout recovery unit. The Endangered Species Act requires that conservation plans be developed and implemented to restore Bull Trout populations to levels that ensure their persistence in the Little Lost River subbasin.
DEQ has determined that water quality has been limited by sediment deposition and elevated stream temperatures due to streambank erosion and reduction of riparian vegetation.
DEQ has developed recommendations for reducing streambank erosion that will ultimately result in beneficial use support through improving streambank stability and subsequently riparian vegetation to reduce temperature. Sediment load reductions are quantified through streambank erosion inventories that estimate streambank erosion based on bank conditions documented along several reaches of each stream. Instream sediment targets have been identified from literature values that are supportive of salmonid spawning and cold water biota. These target values will be used to track the progress of streambank recovery and determine the need for additional management practices to improve water quality. Monitoring will be conducted by land management agencies to determine the adequacy of reductions and management practices.
2000 TMDL: Streams and Pollutants for Which TMDLs Were Developed
- Little Lost River
- Sawmill Creek
- Wet Creek
- Little Lost River Subbasin TMDL (August 2000)
- Little Lost River Subbasin: TMDL Five-Year Review (July 2015)
- Little Lost River Subbasin Assessment and Total Maximum Daily Load: 2015 Temperature Addendum (December 2015)