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Owyhee River (Middle) Subbasin

Data Details
Hydrologic Unit Codes 17050107
Size 290 square miles (185,816 acres)
Water Bodies with EPA-Approved TMDLs (Category 4a) Cabin and Corral Creeks and tributaries, Juniper Creek and tributaries, Middle Fork Owyhee River and tributaries, Noon Creek watershed, North Fork Owyhee River, Pleasant Valley Creek and tributaries
Beneficial Uses Affected Salmonid spawning, cold water aquatic life
Major Land Uses Grazing, agriculture
Date Approved by EPA February 2000 EPA Approval Letter
Date Addendum Approved by EPA July 2012 EPA Approval Letter

Subbasin Characteristics

The North and Middle Fork Owyhee River drainages are located within one 4th-order hydrologic unit in southwest Idaho. They generally drain west from Idaho into Oregon. The existing uses of tributaries of the North and Middle Forks Owyhee River include cold water biota, salmonid spawning, rearing of redband trout, secondary contact recreation, and agricultural water supply. Existing uses of the North and Middle Forks Owyhee River include those uses as well as primary contact recreation, domestic water supply, and special resource waters. Of these uses, only cold water biota, salmonid spawning, and salmonid rearing were affected by pollutants.

2000 Subbasin Assessment and TMDL

Stream temperature data from water bodies within the subbasin show many of the streams’ temperatures exceed the Idaho and Oregon water quality temperature standards.

Some stream segments were also listed for sediment, bacteria, and/or flow alteration. A review of the biological and chemical sediment data available showed no violations of applicable water quality standards for sediment and no impairment to the biological community from sediment. Therefore, TMDLs for sediment were not written; however, there can be no increase to the current sediment loads.

Bacteria was listed as a pollutant of concern for the North Fork Owyhee River. However, sampling indicated bacteria levels did not violate current Idaho or Oregon standards, so a TMDL for bacteria was not written for the North Fork Owyhee River. Flow alteration was listed as a concern for several water bodies, but TMDLs were not prepared for flow alteration. Flow alteration is considered “pollution,” not a “pollutant,” and TMDLs are not required for water bodies impaired by pollution but not by specific pollutants. A TMDL is only required when a pollutant can be identified and in some way quantified.

2000 TMDL: Streams and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Middle Fork Owyhee River Temperature
North Fork Owyhee River Temperature
Big Spring Creek Temperature
Cabin Creek Temperature
Corral Creek Temperature
Juniper Creek (two segments) Temperature
Noon Creek Temperature
Pleasant Valley Creek Temperature
Squaw Creek (two segments) Temperature

2012 Addendum

This document addresses the temperature impairments of 36 assessment units in the Owyhee River watershed in southwest Idaho. The Owyhee River watershed incorporates the Upper, South, and Middle Fork Owyhee River subbasins.

Temperature TMDLs were previously written for many assessment units in the Owyhee River watershed. However, the Idaho Department of Environmental Quality (DEQ) recommended rewriting those TMDLs using more appropriate shade targets based on knowledge of local vegetation types and natural stream widths. This document revises 25 previous TMDLs and establishes 11 new TMDLs.


SubbasinHydrologic Unit Code (HUC)Assessment Units with New TMDLsAssessment Units with Updated TMDLs
Upper Owyhee River170501041110
South Fork Owyhee River1705010502
North and Middle Fork Owyhee River17050107013

2012 Addendum: Assessment Units and Pollutants for Which TMDLs Were Developed

Upper Owyhee River Subbasin

DescriptionAssessment UnitPollutant
Battle Creek upstream of Antelope FlatID17050104SW023_02Temperature
Battle Creek between Antelope Flat and Big Springs CreekID17050104SW023_03Temperature
Battle Creek between Big Springs Creek and Owyhee RiverID17050104SW023_04Temperature
Deep Creek between Hurry Back and Nickel CreeksID17050104SW026_04Temperature (updated)
Deep Creek between Nickel Creek and Owyhee RiverID17050104SW026_05Temperature (updated)
Pole Creek upstream of Mud FlatID17050104SW028_02Temperature (updated)
Pole Creek between Camas Creek and Mud FlatID17050104SW028_03Temperature (updated)
Pole Creek between Camas and Deep CreeksID17050104SW028_04Temperature (updated)
Camas Creek between Big Springs Butte and Pole CreekID17050104SW029_03Temperature
Camel Creek upstream of Sunshine Valley CreekID17050104SW030_02Temperature
Nickel, Smith, and Thomas Creek headwatersID17050104SW031_02Temperature
Nickel, Smith and Thomas Creeks 3rd orderID17050104SW031_03Temperature
Nickel and Smith Creeks 4th orderID17050104SW031_04Temperature
Castle Creek upstream of Skunk CreekID17050104SW032_02Temperature (updated)
Castle Creek between Skunk and Deep CreeksID17050104SW032_03Temperature (updated)
Beaver Creek upstream of Carter CreekID17050104SW033_02Temperature
Beaver Creek between Carter and Trap CreeksID17050104SW033_03Temperature
Beaver Creek between Trap and Deep CreeksID17050104SW033_04Temperature
West Fork Red CanyonID17050104SW034_02Temperature (updated)
East Fork Red Canyon and Red Canyon upstream of Petes CreekID17050104SW034_03Temperature (updated)
Red Canyon between Petes Creek and Owyhee RiverID17050104SW034_04Temperature (updated)

2008 Addemdum

This is an addendum to the Lower Boise River TMDL for sediment and bacteria approved by the US Environmental Protection Agency on January 25, 2000. The addendum provided the Avimor Development and the City of Kuna, Idaho, with wasteload allocations for total suspended solids and E. coli bacteria for a discharge to Dry Creek and Indian Creek, respectively. DEQ also outlines in this addendum the manner in which the sediment reserved for growth shall be allocated to new and existing sources in the future. The bolded changes in the addendum are made on pages 61, 62, 64, and 72 of the original document. Table 15 was revised in June 2012.

South Fork Owyhee River Subbasin

Description Assessment Unit Pollutant
South Fork Owyhee River upstream of Little Owyhee River ID17050105SW001_06 Temperature (updated)
South Fork Owyhee River downstream of Little Owyhee River ID17050105SW001_07 Temperature (updated)

North and Middle Fork Owyhee River Subbasin

Description Assessment Unit Pollutant
Middle Fork Owyhee River upstream of Summit Springs Creek  ID17050107SW004_02 Temperature (updated)
Middle Fork Owyhee River downstream of Summit Springs Creek ID17050107SW004_03 Temperature (updated)
North Fork Owyhee River upstream of Big Springs Creek ID17050107SW008_02 Temperature (updated)
North Fork Owyhee River between Big Spring and Pleasant Valley Creeks ID17050107SW008_03 Temperature (updated)
North Fork Owyhee River between Pleasant Valley and Juniper Creeks, and Juniper Creek between Cabin Creek and North Fork Owyhee River ID17050107SW008_04 Temperature (updated)
North Fork Owyhee River downstream of Juniper Creek ID17050107SW008_05 Temperature (updated)
Pleasant Valley Creek upstream of East Fork Pleasant Valley Creek ID17050107SW009_02 Temperature (updated)
Pleasant Valley Creek between North Fork Owyhee River and East Fork Pleasant Valley Creek ID17050107SW009_03 Temperature (updated)
Noon Creek ID17050107SW010_02 Temperature (updated)
Cabin and Corral Creek headwaters ID17050107SW011_02 Temperature (updated)
Cabin and Corral Creeks3rd order ID17050107SW011_03 Temperature (updated)
Juniper Creek upstream of Buck Creek ID17050107SW012_02 Temperature (updated)
Juniper Creek between Buck and Cabin Creeks ID17050107SW012_03 Temperature (updated)

Subbasin Document(s)

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DEQ Boise Regional Office
1445 N. Orchard St.
Boise, ID 83706
Ph: (208) 373-0550
Fax: (208) 373-0287
Toll Free: (888) 800-3480

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