Official Government Website

Salmon River (Upper and Lower Middle Forks) Subbasin

Data Details
Hydrologic Unit Codes Upper Middle Fork Salmon River Subbasin: 17060205 Lower Middle Fork Salmon River Subbasin: 17060206
Size Upper:1,500 square miles (960,000 acres) Lower: 1,373 square miles (878,720 acres)
Water Bodies with EPA-Approved TMDLs (Category 4a) Beaver Creek, Camas Creek, Castle Creek, Duck Creek, Knapp Creek, Marsh Creek, Silver Creek, Winnemucca Creek, Yellowjacket Creek
Beneficial Uses Affected Cold water aquatic life, primary contact recreation, agricultural water supply, domestic water supply, secondary contact recreation
Major Land Uses Recreation, designated Wilderness
Date Approved by EPA February 2009 EPA Approval Letter

Subbasin Characteristics

The Middle Fork Salmon River is a tributary watershed of the Upper Salmon River basin. The Middle Fork Salmon River flows primarily through the Frank Church-River of No Return Wilderness. It is divided into two subbasins: the Upper (southern) and the Lower (northern). The Middle Fork Salmon River watershed, essentially one of the most pristine in Idaho, is located in Custer, Lemhi, Valley, and Idaho Counties and is contained in portions of the Boise, Salmon, Challis, Nez Perce, and Payette National Forests. No major population centers are located within the watershed; the nearest towns include Stanley, Challis, and Salmon.

2008 Subbasin Assessment and TMDL

The primary pollutant of concern in the subbasin is thermal loading related to exposed streambanks. Temperature TMDLs were developed for Marsh, Knapp, Beaver, Winnemucca, Camas, Castle, Silver, Duck, and Yellowjacket Creeks. Beaver Creek and Winnemucca Creek show the greatest lack of shade, with both streams needing more than 50% reduction in solar loads.

EPA lists specific circumstances in which a water body can be placed in section 4b of the Integrated Report. This section is for those water bodies for which some or all of certain measures that will result in attainment of water quality standards in that water body in a reasonable time have already been implemented. DEQ’s assertion is that Bear Valley and Elk Creeks meet the above criteria, so TMDLs were not developed for these creeks.

DEQ also recommends some streams be removed from the §303(d) list. These streams either showed full support of beneficial uses or are ephemeral or low flow streams.

2008 TMDL: Streams and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Marsh Creek Temperature
Knapp Creek Temperature
Beaver Creek Temperature
Winnemucca Creek Temperature
Camas Creek Temperature
Castle Creek Temperature
Silver Creek Temperature
Duck Creek Temperature
Yellowjacket Creek Temperature

2011 Bear Valley Creek 4b Justification

The Bear Valley Creek 4b Justification document, drafted jointly by the U.S. Forest Service and DEQ, addresses four assessment units within the Upper Middle Fork Salmon River subbasin that have been determined to meet the requirements of section 4b of the Integrated Report. The pollutant of concern is sediment. Numerous actions have already been implemented by the Forest Service to reduce the amount of sediment entering stream reaches, and additional remediation is planned to reduce road sediments.

Subbasin Document(s)

This accordion will not appear on the screen

DEQ Idaho Falls Regional Office
900 N. Skyline Drive, Suite B
Idaho Falls, ID 83402
Ph: (208) 528-2650
Fax: (208) 528-2695
Toll Free: (800) 232-4635

ver: 3.5.1 | last updated:
Jump back to top of page button