Boise River (Lower) Nutrient/Tributary Subbasin

Subbasin at a Glance

Hydrologic Unit Code	17050114
Size	1,290 square miles
§303(d) Listed Stream Segments	Lower Boise River (2 segments), Blacks Creek, Fivemile Creek, Tenmile Creek, Mason Creek, Indian Creek, Sand Hollow Creek, Willow Creek, Cottonwood Creek, Dixie Drain (this document does not address Willow Creek, Cottonwood Creek, or Dixie Drain)
Beneficial Uses Affected	Cold water biota, salmonid spawning, domestic water supply, primary and secondary contact recreation, special resource water
Pollutants of Concern	Nutrients, sediment, dissolved oxygen, temperature, oil and grease
Major Land Uses	Range, forest, agriculture, urban
Date Approved by U.S. EPA	Subbasin assessment only; not subject to E.P.A. approval

Overview

The lower Boise River watershed is located in southwest Idaho. The lower Boise River itself is a 64-mile stretch that flows in a northwesterly direction through Ada and Canyon counties and the cities of Boise and Caldwell. It originates at Lucky Peak Dam and flows into the Snake River near Parma. Two segments of the lower Boise River are listed for nutrients on Idaho's 1998 §303(d) list and eight tributaries are listed for a variety of pollutants.

The Snake River-Hells Canyon TMDL is scheduled to be completed in 2001. Nutrients and sediment are listed as pollutants of concern in that TMDL and will be addressed by assigning load allocations to the major tributaries to the Snake River, including the lower Boise River. When the Snake River-Hells Canyon TMDL allocates a nutrient load to the lower Boise River, load reductions from the tributaries to the lower Boise River will be necessary to meet the Snake River-Hells Canyon load allocation.

Summary of Assessment Outcomes

Water Body	Listed Pollutants	Recommendations
Lower Boise River	Nutrients	Delist for nutrients
Blacks Creek	Dissolved oxygen, sediment, nutrients	Delist for dissolved oxygen, sediment, nutrients
Fivemile Creek	Dissolved oxygen, sediment, nutrients	Delist for dissolved oxygen, sediment, nutrients; list for bacteria
Tenmile Creek	Dissolved oxygen, sediment, nutrients	Delist for dissolved oxygen, sediment, nutrients; list for bacteria
Mason Creek	Dissolved oxygen, sediment, nutrients	Delist for dissolved oxygen, sediment, nutrients; list for bacteria
Indian Creek	Dissolved oxygen, oil and grease, sediment, nutrients, temperature	Delist for nutrients, oil, and grease; no TMDL for dissolved oxygen or sediment, but leave on §303(d) list; temperature will be addressed in the future; list for bacteria
Sand Hollow Creek	Dissolved oxygen, sediment, nutrients	Delist for nutrients, oil, and grease; no TMDL for dissolved oxygen or sediment, but leave on §303(d) list; temperature will be addressed in the future; list for bacteria

Subbasin Documents

Lower Boise River Nutrient & Tributary Subbasin Assessments (December 2001)
Lower Boise River Nutrient Subbasin Assessment (December 2001)
Fivemile and Tenmile Creek Subbasin Assessment (December 2001)
Mason Creek Subbasin Assessment (December 2001)
Blacks Creek Subbasin Assessment (December 2001)
Lower Boise River Tributary Subbasin Assessment Appendices List (May 2001)
Response to Comments Record Draft Lower Boise River Nutrient Subbasin Assessment (January 2002)

Department of
Environmental Quality

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