|Hydrologic Unit Codes||17060209 (Lower Salmon River) 17060101 (Hells Canyon)|
|Size||Lower Salmon River: 1,241 square miles (794,000 acres) Hells Canyon: 542 square miles (347,000 acres)|
|Water Bodies with EPA-Approved TMDLs (Category 4a)||Lower Salmon River: Allison Creek, Billy Creek, Cottonwood Creek, Deep Creek, Grave Creek, Johns Creek, Rice Creek and tributaries, Rock Creek, Telcher Creek Hells Canyon: Divide Creek and tributaries, Snake River, Wolf Creek and tributaries|
|Beneficial Uses Affected||Cold water aquatic life, salmonid spawning, primary contact recreation, secondary contact recreation|
|Major Land Uses||Lower Salmon River: agriculture, logging, roads, livestock grazing, timber harvest, mining, and recreation Hells Canyon: livestock grazing along the river corridor, timber harvest, recreation, agriculture, and residences|
|Date Approved by EPA||April 2013 EPA Approval Letter|
The Lower Salmon River subbasin is comprised of 65 water bodies located in west-central Idaho and includes the Salmon River from its mouth to French Creek. The subbasin encompasses approximately 794,000 acres, draining into the Snake River at river mile 188.2. Most of the subbasin is private land, followed by land managed by the United States Forest Service (USFS), Bureau of Land Management (BLM), Idaho Department of Fish and Game (IDFG), and Idaho Department of Lands (IDL).
2010 Subbasin Assessment and TMDL
Nine tributaries in the lower Salmon River subbasin were listed as not meeting state water quality standards in Section 5 of Idaho’s 2008 Integrated Report: Billy Creek, Cottonwood Creek, Allison Creek, Rice Creek, Rock Creek, Graves Creek, Johns Creek, Deep Creek, and Deer Creek.
The Hells Canyon (Snake River) subbasin is comprised of 28 water bodies. The subbasin encompasses approximately 347,000 acres, extending from Hells Canyon Dam to the confluence with the Salmon River. This section of the Snake River is characterized as a rapid-flowing, narrow river with steep canyon walls and stretches of whitewater. The flow and volume is almost completely dictated by the outflow from Hells Canyon Reservoir. This segment, from the dam to the confluence with the Salmon River, supports recreational uses such as boating, rafting, and sport fishing year round. Two tributaries in the Hells Canyon subbasin were listed as not meeting state water quality standards in Section 5 of Idaho’s 2008 Integrated Report: Wolf Creek and Divide Creek.
DEQ conducted a water quality sampling project beginning in March 2007 and sampling biweekly for approximately one year. Based on the data collected, bacteria, sediment, and temperature TMDLs were developed. In addition, because they were found to no longer be impairing water quality, sediment was removed as a pollutant impairing Allison, Cottonwood, Deer, Divide, Graves, Rice, and Wolf Creeks and nutrients, temperature, and bacteria were removed from the list of Deep Creek pollutants. No wasteload allocations were developed since there are currently no permitted sources that discharge to the assessed water bodies.
2010 TMDL: Streams and Pollutants for Which TMDLs Were Developed
|Billy Creek||Bacteria, sediment|
|Deep Creek (source to unnamed tributary)||Temperature|
|Divide Creek (source to mouth)||Temperature|
|Graves Creek (headwaters to unnamed tributary, unnamed tributary to Rock Creek)||Bacteria|
|Johns Creek (Rock Creek source to Graves Creek)||Sediment, bacteria, temperature|
|Rice Creek (Rice Creek tributary)||Temperature|
|Rock Creek (source to grave)||Sediment, bacteria, temperature|
|Wolf Creek (Basin Creek to mouth)||Temperature|