Boise River (South Fork) Subbasin

Subbasin at a Glance

Hydrologic Unit Code	17050113
Size	835,645 acres
§303(d) Listed Stream Segments	Anderson Ranch Reservoir and tributaries, Fall Creek, Lime Creek, Little Camas Creek Reservoir, Little Smoky Creek, Lower Willow Creek, Moores Creek, Rattlesnake Creek, Smith Creek, South Fork Boise River, Upper Willow Creek
Beneficial Uses Affected	Aquatic life support, contact recreation, water supply, wildlife habitats, aesthetics
Pollutants of Concern	Sediment, temperature, unknown
Major Land Uses	Predominantly uninhabited federal land managed by the U.S. Forest Service; forestry, roads, mining, agriculture/livestock, recreation
Date Approved by U.S. EPA	March 2009 EPA Approval Letter

Overview

The South Fork Boise River Subbasin is located in southwestern Idaho, east of Boise and predominantly in Elmore and Camas counties. The watershed includes the South Fork Boise River upstream of the slack water of Arrowrock Reservoir, Anderson Ranch Reservoir, and all South Fork Boise River tributaries upstream to the headwaters. The subbasin area is primarily federally owned and administered. Prairie, Pine, and Featherville are the only recognized communities in the watershed that have year-round residents; second/summer/recreational homes are found in numerous sub-divided areas throughout the watershed. Access is provided by many miles of U.S. Forest Service-maintained roads and by county-owned or -maintained roads.

The subbasin consists of 34 separate water body assessment units (previously identified as stream segments. Of these, 14 were identified as water quality limited and were placed on the 2002 §303(d) list. Of these, 5 (listed below) are identified in the subbasin assessment as needing water quality improvement plans known as Total Maximum Daily Loads (TMDLs) to address temperature. Temperature is a water quality factor integral to the life cycle of fish and other aquatic species. Elevated stream temperatures can be harmful to fish at all life stages. Sources of elevated temperature are anthropogenic alterations related to roads, farming, grazing, mining, timber harvest, community or domestic development, or other activities, that reduced stream shade or altered the stream in a way that resulted in increased stream temperatures.

In addition, the subbasin assessment identifies several streams to be added to the state's list of impaired waterbodies for flow and habitat alteration in the next Integrated Report and others to be removed for sediment and unknown pollutants.

Streams and Pollutants for Which TMDLs Were Developed

Smith Creek: Temperature
Lime Creek: Temperature
N. Fork Lime Creek: Temperature
Middle Fork Lime Creek: Temperature
S. Fork Lime Creek: Temperature

Subbasin Document

South Fork Boise River Subbasin Assessment, Total Maximum Daily Load, And Five-Year Review (December 2008)

Department of
Environmental Quality

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