| Data | Details |
|---|---|
| Hydrologic Unit Codes | 17050108 |
| Size | Approximately 602 square miles (385,000 acres) in Idaho (approximately 1,156 square miles [740,000 acres] total) |
| Water Bodies with EPA-Approved TMDLs (Category 4a) | Chimney Creek, Cow Creek, Jordan and Upper Jordan Creeks, Louisa Creek watershed, Meadow Creek, Rock Creek, Soda Creek, Spring Creek, Swisher Creek |
| Beneficial Uses Affected | Cold water aquatic life, primary contact recreation, salmonid spawning |
| Major Land Uses | Irrigated agriculture, rangeland, forest, mining, riparian |
| Date Approved by EPA | April 2011 EPA Approval Letter |
Subbasin Characteristics
The Jordan Creek subbasin encompasses a large area in southwest Idaho and southeast Oregon. The headwaters of Jordan Creek originate in the western section of the Owyhee Mountains, in southwest Idaho, flowing mostly west into Oregon, entering near the community of Jordan Valley. This document addresses only those water bodies in the watershed in Idaho.
A majority of the population in the subbasin is associated with small homesteads, ranches, and farms. Jordan Valley, Oregon, is the only identifiable municipality with permanent year-round residents. The historic town of Silver City, Idaho, is also located within the watershed but is composed mostly of part-time or weekend residents.
2010 Subbasin Assessment and TMDL
Overall, there are seven segments within the Jordan Creek subbasin that were placed on the 2002 §303(d) list, including two segments of Jordan Creek. The remaining water bodies are tributaries to Jordan Creek.
TMDLs were developed to address elevated methylmercury levels in fish tissue on the upper and lower segments of Jordan Creek, and a sediment TMDL was developed for Soda Creek. A temperature TMDL was also completed.
While flow alteration was listed as a pollutant for Jordan Creek, it does not require a TMDL. The US Environmental Protection Agency considers certain unnatural conditions, such as flow alteration, that are not the result of the discharge of a specific pollutant as “pollution.” 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.
Several other pollutants—such as oil and grease, pesticides, and bacteria—were not found to be exceeding water quality standards or impairing beneficial uses; therefore, TMDLs were not developed for these pollutants and it was recommended they be removed from the §303(d) list.
This document was submitted to EPA in June 2010 and amended in December 2010. In April 2011, EPA disapproved the TMDLs submitted for mercury in Jordan Creek and approved the TMDLs submitted for temperature and sediment. EPA intends to develop TMDLs for mercury.
2010 TMDL: Streams and Pollutants for Which TMDLs Were Developed
| Stream | Pollutants |
|---|---|
| Cow Creek | Temperature |
| Jordan Creek | Temperature |
| Louisa Creek | Temperature |
| Meadow Creek | Temperature |
| Rock Creek | Temperature |
| Soda Creek | Temperature, Sediment |
| Spring Creek | Temperature |
Subbasin Document(s)
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