| Data | Details |
|---|---|
| Hydrologic Unit Code | 17040212 |
| Size | 2,438 square miles (1,536,880 acres) |
|
Water Bodies with EPA-Approved TMDLs (Category 4a) |
Billingsley Creek, Briggs Creek, Cedar Draw, Clear Creek, Clear Lakes, Clover Creek, Deep Creek, Dry Creek, McMullen Creek, Mud Creek, North/Dry Cottonwood Creek, Pioneer Reservoir, Riley Creek, Rock Creek, Sand Springs, Snake River and tributaries, tributaries to Yahoo and Deep Creeks, Vinyard Creek, West Fork Dry Creek |
| Beneficial Uses Affected | Cold water aquatic life, salmonid spawning, primary and secondary contact recreation |
| Major Land Uses | Rangeland, agriculture |
| Date Mid-Snake River TMDL Approved by EPA | April 1997 EPA Approval Letter |
| Date Approved by EPA | August 2000 EPA Approval Letter |
| Date Modification Approved by EPA | September 2005 EPA Approval Letter |
| Date City of Twin Falls TSS Revision Approved by EPA |
March 2011 |
Subbasin Characteristics
The Upper Snake-Rock subbasin is located in southern Idaho, primarily in Gooding, Jerome, and Twin Falls Counties. Over 95% of the subbasin is a Snake River Basin/High Desert ecoregion. Its topography consists of tablelands with medium to high relief, and its vegetation is made up predominantly of a sagebrush-grass zone with minimal riparian vegetation in the Middle Snake River or its tributaries. The land use in the subbasin is 54% desert shrublands (on which grazing is a major activity) and 41% agricultural land (both irrigated and dryland).
1999 Subbasin Assessment and TMDL
In the Upper Snake-Rock subbasin, 31 water bodies/stream segments were listed on the 1996 §303(d) list, including 10 segments of the middle Snake River. The TMDL covers 93 miles of the Snake River, including 28 named tributaries.
The middle Snake River TMDL, discussed below, also covers portions of this subbasin.
The middle Snake River is a managed water system where normal flow regimes are no longer present, which allows sediment to accumulate. In general, the middle Snake River and its tributaries are impacted by runoff from irrigated crop production, rangeland, pastureland, animal holding areas, feedlots, dredging, hydro-modification, and urban runoff. Natural springs have exhibited hydro-modification and streambank modification from activities relating to sedimentation, aquaculture, hydropower, irrigated crop production, and land development.
TMDLs were not written for ammonia, nitrogen, pesticides, oil and grease, or temperature. Data did not show that nitrogen, pesticides, or oil and grease were exceeding water quality standards or impacting beneficial uses. It is recommended that pesticides and oil and grease be removed from the §303(d) list; nitrogen levels will continue to be reviewed by DEQ. Clover Creek was found to be polluted by ammonia, but ammonia is not listed on the §303(d) list for Clover Creek. It is recommended that ammonia be added to the next §303(d) list for Clover Creek; a TMDL will be completed after this occurs. Temperature TMDLs have been deferred until after new water quality standards are developed for temperature.
1999 TMDL: Streams and Pollutants for Which TMDLs Were Developed
| Stream | Pollutants |
|---|---|
| Alpheus Creek | Sediment (total suspended solids), phosphorus |
| Billingsley Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Blind Canyon Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Cedar Draw | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Clear Springs | Sediment (total suspended solids), phosphorus |
| Clover Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Cottonwood Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Crystal Springs | Sediment (total suspended solids), phosphorus |
| Deep Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Dry Creek (2 segments) | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Dry Creek (West Fork) | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Ellison Creek | Sediment (total suspended solids), phosphorus |
| McMullen Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Mud Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Riley Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Rock Creek | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Thousand Springs Creek | Sediment (total suspended solids), phosphorus |
| Vineyard Creek | Sediment (total suspended solids), phosphorus |
| Bliss Reservoir | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Lower Salmon Falls Reservoir | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Pioneer Reservoir | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Shoshone Falls Reservoir | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Upper Salmon Falls Reservoir | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
| Middle Snake River (10 segments) | Sediment (total suspended solids), pathogens (fecal coliform bacteria), phosphorus |
1997 Middle Snake River Watershed Assessment and TMDL
| Data | Details |
|---|---|
| Hydrologic Unit Codes | 17040212 (Upper Snake-Rock Subbasin) 17040213 (Salmon Falls Subbasin) |
| Size | 94 square miles (60,160 acres) |
| Beneficial Uses Affected | Aquatic life, primary and secondary contact recreation |
| Major Land Uses | Irrigated agriculture, confined animal feeding operations, food processing, aquaculture, urban, hydroelectric development |
2011 Addendum: Streams and Pollutants for Which TMDLs Were Developed
| Data | Details |
|---|---|
| Hydrologic Unit Codes | 17040212 (Upper Snake-Rock Subbasin) 17040213 (Salmon Falls Subbasin) |
| Size | 94 square miles (60,160 acres) |
| Beneficial Uses Affected | Aquatic life, primary and secondary contact recreation |
| Major Land Uses | Irrigated agriculture, confined animal feeding operations, food processing, aquaculture, urban, hydroelectric development |
1997 TMDL: Streams and Pollutant for Which TMDLs Were Developed
| Data | Details |
|---|---|
| 14 sections of the middle Snake River, including Bliss, Shoshone Falls, Upper Salmon Falls, and Lower Salmon Falls Reservoirs | Total phosphorus |
Aquaculture Wasteload Allocations
- Upper Snake Rock TMDL Modification Part 1 (February 2004)
- Upper Snake Rock TMDL Modification Part 2 (April 2005)
- Upper Snake Rock TMDL Modification Part 3 (May 2005)
Subbasin Document(s)
- Middle Snake River Watershed Management Plan: Phase 1 TMDL Total Phosphorus (January 1997)
- The Upper Snake Rock Watershed Management Plan: The Upper Snake Rock Subbasin Assessment & the Upper Snake Rock Total Maximum Daily Load (December 1999)
- TMDL Executive Summary: Upper Snake/Rock Subbasin TMDL (July 2000)
- The Upper Snake Rock TMDL Modification (July 2005)
- The Upper Snake Rock Implementation Plan (June 2001)
- Upper Snake Rock Subbasin TMDL (2000 & 2005) City of Twin Falls TSS Revision (January 2011)
- Upper Snake Rock/Middle Snake TMDLs (HUC ID17040212): 5-Year TMDL Review (April 2010)
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