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Goose Creek Subbasin

Data Details
Hydrologic Unit Codes 17040211
Size 692 square miles (442,880 acres) in Idaho 1,120 square miles (716,800 acres) total
Water Bodies with EPA-Approved TMDLs (Category 4a) Beaverdam Creek, Birch Creek and tributaries, Cold Creek, Goose Creek, Little Cottonwood Creek, Trapper Creek, Trout Creek
Beneficial Uses Affected Cold water aquatic life, salmonid spawning, secondary contact recreation
Major Land Uses Range, forest, irrigated agriculture, urban
Date Approved by EPA July 2004 EPA Approval Letter
Date Addendum Approved by EPA/td> April 2012 EPA Approval Letter

Subbasin Characteristics

The general physical and biological characteristics of the Goose Creek subbasin have a strong influence on the water quality of the subbasin. Land use in the subbasin is predominantly rangeland. Irrigated agriculture also exists in the lower-elevation, northern portion of the subbasin where water is either pumped from the ground or diverted from Goose Creek Reservoir. The major population center of the subbasin is the town of Oakley. The subbasin contains three different water sources. The first is runoff from the snowpack and other precipitation events in the mountainous region to the east and west. The second is the Goose Creek-Golden Valley aquifer below Oakley, which is part of the Eastern Snake River Plain aquifer. The final source is a geothermal layer that feeds several geothermal springs along the ecoregional boundary.

2003 Subbasin Assessment and TMDL

The original TMDL document addresses the nine water bodies in the Goose Creek subbasin that were placed on the §303(d) list of impaired water bodies. Three additional water bodies (Emery Creek, Little Cottonwood Creek, and Left Hand Fork Beaverdam Creek) were also assessed based on past data that showed bacterial contamination.

The water quality of the Goose Creek subbasin is generally of high quality. Of the nine original listed water bodies, DEQ proposes to delist the following four: Lower Goose Creek Reservoir, Mill Creek, Blue Hill Creek, and Big Cottonwood Creek. Of the three additional water bodies, TMDLs were written for two; it was determined that Emery Creek is not impaired by bacterial contamination.

Goose Creek, Trapper Creek, and Lower Goose Creek Reservoir are listed for flow alteration. However, the US Environmental Protection Agency does not believe that flow (or lack of flow) is a pollutant as defined by the Clean Water Act. Since TMDLs are not required for water bodies impaired by pollution but not pollutants, TMDLs were not developed for flow alteration.

2003 TMDL: Streams and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Goose Creek Temperature, sediment
Trapper Creek Nutrients, sediment
Birch Creek Nutrients, bacteria
Cold Creek Temperature
Beaverdam Creek Nutrients, temperature, bacteria, sediment, dissolved oxygen
Little Cottonwood Creek Bacteria
Left Hand Fork Beaverdam Creek Nutrients, sediment, bacteria

2012 Addendum

This document was developed to address 14 assessment units (AUs) listed in Category 5 for impaired waters on Idaho’s 2010 Integrated Report. Additional unlisted AUs were evaluated for possible temperature violations. Investigation by DEQ showed that excess sediment was determined to be impairing water quality in two reaches of the Big Lost River: the reach above Bartlett Point Road and the reach above Mackay Reservoir. Sediment water quality targets were met in Bear, Pinto, Grant, and Garden Creeks. Bacteria was found to exceed the target for supporting secondary contact recreation as a beneficial use in Sage Creek; Wildhorse Creek was found to be meeting bacteria water quality targets. Investigation also showed that all streams examined for temperature impairment lacked shade to some degree. Potential natural vegetation TMDLs were completed for AUs of the Big Lost River, East Fork Big Lost River, Antelope Creek, Leadbelt Creek, Twin Bridges Creek, and the Thousand Springs Creek tributaries.

2012 Addendum: Streams and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Upper Goose Creek and tributaries Temperature
Trout Creek and tributaries Temperature

Subbasin Document(s)

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DEQ Twin Falls Regional Office
650 Addison Avenue West, Suite 110
Twin Falls, ID 83301
Ph: (208) 736-2190
Fax: (208) 736-2194
Toll Free: (800) 270-1663

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