| Data | Details |
|---|---|
| Hydrologic Unit Codes | 17050105 |
| Size | 1,850 square miles (1,183,923 acres) total – 242 square miles (154,810 acres) in Idaho |
| Water Bodies with EPA-Approved TMDLs (Category 4a) | South Fork Owyhee River |
| Beneficial Uses Affected | Primary contact recreation, secondary contact recreation, cold water aquatic life, salmonid spawning, domestic water supply, agricultural water supply |
| Major Land Uses | Livestock grazing |
| Date Approved by EPA | March 2000 EPA Approval Letter |
| Date Addendum Approved by EPA | July 2012 EPA Approval Letter |
Subbasin Characteristics
The South Fork Owyhee River is located in the far southwestern portion of Idaho and originates in the north-central portion of Nevada. The area is predominately open desert and deep canyons.
The hydrology of the South Fork Owyhee River is the river itself. No perennial streams feed the river within Idaho. The South Fork Owyhee River is subject to “flashy” flow conditions with peak flows occurring anytime from January to June. There are no major impoundments in either Nevada or Idaho.
1999 Subbasin Assessment and TMDL
With the exception of temperature, water column chemistry meets Idaho water quality standards. Water temperatures often exceed water quality standards for the protection of both cold water biota and salmonid spawning. Warm water temperatures may be the most important factor limiting the presence of trout species. There is no indication that sediments are impairing beneficial uses.
A TMDL for temperature is an appropriate vehicle for addressing temperature concerns in the South Fork Owyhee River. A load capacity is assigned in this original TMDL, which includes a load allocation for the water as it enters the state of Idaho.
If the South Fork Owyhee River is able to meet Idaho temperature criteria at the Idaho/Nevada border, the argument could be made that the additional increase in Idaho is natural, and site-specific criteria could be developed. Alternatively, if the South Fork Owyhee River cannot meet Idaho temperature criteria at the border, then Idaho and Nevada will need to work together to develop appropriate site-specific criteria.
1999 TMDL: Streams and Pollutants for Which TMDLs Were Developed
| Stream | Pollutants |
|---|---|
| South Fork Owyhee River | 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.
| Subbasin | Hydrologic Unit Code (HUC) | Assessment Units with New TMDLs | Assessment Units with Updated TMDLs |
|---|---|---|---|
| Upper Owyhee River | 17050104 | 11 | 10 |
| South Fork Owyhee River | 17050105 | 0 | 2 |
| North and Middle Fork Owyhee River | 17050107 | 0 | 13 |
2012 Addendum: Assessment Units and Pollutants for Which TMDLs Were Developed
Upper Owyhee River Subbasin
| Description | Assessment Unit | Pollutant |
|---|---|---|
| Battle Creek upstream of Antelope Flat | ID17050104SW023_02 | Temperature |
| Battle Creek between Antelope Flat and Big Springs Creek | ID17050104SW023_03 | Temperature |
| Battle Creek between Big Springs Creek and Owyhee River | ID17050104SW023_04 | Temperature |
| Deep Creek between Hurry Back and Nickel Creeks | ID17050104SW026_04 | Temperature (updated) |
| Deep Creek between Nickel Creek and Owyhee River | ID17050104SW026_05 | Temperature (updated) |
| Pole Creek upstream of Mud Flat | ID17050104SW028_02 | Temperature (updated) |
| Pole Creek between Camas Creek and Mud Flat | ID17050104SW028_03 | Temperature (updated) |
| Pole Creek between Camas and Deep Creeks | ID17050104SW028_04 | Temperature (updated) |
| Camas Creek between Big Springs Butte and Pole Creek | ID17050104SW029_03 | Temperature |
| Camel Creek upstream of Sunshine Valley Creek | ID17050104SW030_02 | Temperature |
| Nickel, Smith, and Thomas Creek headwaters | ID17050104SW031_02 | Temperature |
| Nickel, Smith and Thomas Creeks 3rd order | ID17050104SW031_03 | Temperature |
| Nickel and Smith Creeks 4th order | ID17050104SW031_04 | Temperature |
| Castle Creek upstream of Skunk Creek | ID17050104SW032_02 | Temperature (updated) |
| Castle Creek between Skunk and Deep Creeks | ID17050104SW032_03 | Temperature (updated) |
| Beaver Creek upstream of Carter Creek | ID17050104SW033_02 | Temperature |
| Beaver Creek between Carter and Trap Creeks | ID17050104SW033_03 | Temperature |
| Beaver Creek between Trap and Deep Creeks | ID17050104SW033_04 | Temperature |
| West Fork Red Canyon | ID17050104SW034_02 | Temperature (updated) |
| East Fork Red Canyon and Red Canyon upstream of Petes Creek | ID17050104SW034_03 | Temperature (updated) |
| Red Canyon between Petes Creek and Owyhee River | ID17050104SW034_04 | Temperature (updated) |
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 |
| 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)
- Upper Owyhee Watershed Subbasin Assessment and Total Maximum Daily Load Owyhee County, Idaho (January 2003)
- Upper Owyhee Watershed TMDL Implementation Plan for Agriculture (October 2004)
- Upper Owyhee River TMDL Five-Year Review (June 2009)
- Owyhee River Watershed Total Maximum Daily Load Temperature Addendum: North and Middle Fork Owyhee, South Fork Owyhee, and Upper Owyhee (June 2012)
- Owyhee River Watershed TMDL Temperature Addendum: North and Middle Fork Owyhee, South Fork Owyhee, and Upper Owyhee Agriculture Implementation Plan (May 2017)