Department of
Environmental Quality

The Idaho Falls Regional Office monitors water quality for some of Idaho’s most popular recreation destinations and world-class fisheries—from Henrys Lake to the Salmon River in the Frank Church-River of No Return Wilderness to Redfish Lake at the base of the Sawtooth Mountains. Nine Idaho counties are located in this region and, while water bodies in the area are adversely impacted by certain pollutants, the overall water quality is exceptional.

DEQ monitors temperature to identify exceedances of water quality standards that would adversely affect fish spawning and rearing. DEQ also conducts biological water quality monitoring that evaluates the stream habitat, bugs (macroinvertebrates), and fishery.

Some streams in this region experience excessive sediment deposition and elevated temperatures due to bank erosion and reduction of riparian vegetation caused by roads, recreation, and livestock grazing. These pollutant sources have caused some streams to be §303(d) listed, which means the water body does not meet Idaho state water quality standards as defined in the Clean Water Act. The remedy requires development of water quality improvement plans known as TMDLs (Total Maximum Daily Loads). Stream flow and habitat alterations such as irrigation diversions, historic mining practices, past timber harvests, residential and municipal development have also impacted water quality in some water bodies in the region.

DEQ works with local watershed advisory groups who provide valuable input into developing TMDLs. It partners with other state and federal agencies as well as non-profit organizations such as the Bureau of Land Management, US Forest Service, Idaho Department of Lands, Upper Salmon Basin Model Watershed Program, and Trout Unlimited to monitor, evaluate and implement water quality enhancement projects as needed.

Subbasin Assessments and Total Maximum Daily Loads

Listed below are subbasins in which subbasin assessments (SBAs) and/or total maximum daily loads (TMDLs) have been completed for water bodies in DEQ's Idaho Falls Region. Click on the subbasin name to link to an overview of water quality in the subbasin, a list of streams and pollutants for which TMDLs were developed, and related documents, including subbasin assessments and TMDLs, addenda, implementation plans, and five-year reviews. (Access the statewide list of SBAs/TMDLs here.)

• Beaver-Camas Subbasin
• Big Lost River Subbasin
• Birch Creek Subbasin
• Henrys Fork (Upper and Lower) Subbasin
• Idaho Falls Subbasin
• Lemhi River Subbasin
• Little Lost River Subbasin
• Medicine Lodge Subbasin
• Pahsimeroi River Subbasin
• Palisades Subbasin
• Salmon River (Middle) - Chamberlain Creek Subbasin
• Salmon River (Middle) - Panther Creek Subbasin
• Salmon River, Middle Fork Subbasin
• Teton River Subbasin
• Willow Creek Subbasin

Ground Water Studies and Reports

• Groundwater Quality Investigation and Wellhead Protection Study, City of Ashton, Idaho (Technical Report 15. August 2001)
• Follow-up Sampling for Bacteria, Nitrates, Major Ions, Stable Isotops, and Tritium 2009-2010: Ashton-Drummond Nitrate Priority Area (Technical Report 43, December 2011)
  
• Arsenic Occurrence in Ground Water in the Market Lake Area, Idaho (Technical Report 34. November 2008)
• Ground Water Vulnerability Assessment, Snake River Plain, Southern Idaho (Technical Report 2. April 1991)
• Preliminary Assessment of Hydrogeology and Water Qualtiy in Ground Water in Teton County, Idaho (March 2007)

Surface Water Studies and Reports

• Blackbird Creek Use Attainability Analysis (September 1997)
• Bucktail Creek Use Attainability Analysis | Appendix 1 | Appendix 2 | Appendix 3 | Appendix 4 (February 2002)
• Thompson Creek: Evaluation of Proposed New Point Source Discharges to a Special Resource Water and Mixing Zone Determinations: Thompson Creek Mine facility, Upper Salmon River Subbasin (December 2000)