Little Salmon River Subbasin

Subbasin at a Glance

Hydrologic Unit Code	17060210
Size	576 square miles
§303(d) Listed Stream Segments	Little Salmon River (3 segments), Big Creek, Elk Creek, Indian Creek, Shingle Creek, Brundage Reservoir
Beneficial Uses Affected	Cold water, salmonid spawning, primary contact recreation, domestic water supply, special resource water
Pollutants of Concern	Sediment, temperature
Major Land Uses	Forestry, rangeland (grazing), recreation
Date Approved by U.S. EPA	March 2006

Overview

The Little Salmon River Watershed lies entirely in central Idaho. It originates at about 6,280 feet off of Blue Bunch Ridge. The watershed is 45 miles long, and the river flows north for 51 miles to its confluence with the Salmon River at Riggins. U.S. Highway 95 parallels most of the river.

The Little Salmon River from Big Creek to Round Valley Creek was found to have beneficial uses impaired by temperature, nutrients, and bacteria. TMDLs were developed for these pollutants. Potential natural vegetation (shade) was used as a surrogate for temperature because this would achieve natural background conditions.

The Little Salmon River from Vicks Creek to Big Creek was found to have beneficial uses impaired by temperature. A TMDL was developed for temperature.

Big Creek was listed for an unknown pollutant. Elevated nutrient and bacteria levels were found in the creek. TMDLs were developed for nutrients and bacteria.

The Little Salmon River from Round Valley Creek to the mouth showed support of beneficial uses. However, DEQ was unable to analyze the effect of coarse sediment in the system. DEQ proposes to list the Little Salmon River from Round Valley Creek to the mouth for habitat alteration and delist it for sediment. This listing is on the basis of DEQ Beneficial Use Reconnaissance Program (BURP) scores that did not indicate impairment and on low suspended sediment data. However, the listing for habitat alteration is in recognition that the system was changed due to the construction of the highway and the channel remains constricted, leading to potential coarse sediment loading problems. Idaho's antidegradation policy applies in this case and existing uses must be maintained and protected from any activities that would result in human caused excess sediment delivery to the system.

Elk Creek, Indian Creek, and Shingle Creek were all listed for sediment. Beneficial uses were fully supported in these watersheds and TMDLs are not necessary.

Brundage Reservoir was monitored weekly for temperature from early July through Mid-August 2005. Monitoring occurred in late afternoon and early evening when reservoir temperatures would be highest. No violations of the cold water temperature standard were seen. Brundage Reservoir is proposed for delisting for temperature.

Goose Creek was assessed as part of DEQ's BURP program and was found to have impaired beneficial uses. Goose Creek is proposed for listing on the next §303(d) list for an unknown pollutant. Lack of flow may be a causal factor in impairment of beneficial uses for Goose Creek. Therefore, a TMDL was not developed at this time. DEQ did not have the time during the writing of this TMDL to characterize the flows in Goose Creek to determine if intermittence was impairing beneficial uses.

Streams and Pollutants for Which TMDLs Were Developed

Little Salmon River (Big Creek to Round Valley Creek): Temperature, bacteria, nutrients
Little Salmon River (Vicks Creek to Big Creek): Temperature
Big Creek: Bacteria,nutrients

Subbasin Documents

Little Salmon River Subbasin Assessment and TMDL (February 2006)
Little Salmon River Total Maximum Daily Load Implementation Plan for Agriculture, Forestry, and Urban/Suburban Activities (November 2008)
Little Salmon River Subbasin Assessment and Total Maximum Daily Load: Five-Year Review (April 2012)

Department of
Environmental Quality

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