Department of
Environmental Quality

Subbasin at a Glance

Overview

The North and Middle Fork Owyhee River drainages are located within one fourth- order hydrologic unit in southwest Idaho. They generally drain west from Idaho into Oregon. The existing uses of tributaries of the North and Middle Forks Owyhee River include cold water biota, salmonid spawning, rearing of redband trout, secondary contact recreation, and agricultural water supply. Existing uses of the North and Middle Forks Owyhee River include those uses as well as primary contact recreation, domestic water supply, and special resource waters. Of these uses, only cold water biota, salmonid spawning, and salmonid rearing were affected by pollutants.

Stream temperature data from water bodies within the North and Middle Fork Owyhee hydrologic unit show many of the streams' temperatures exceed the Idaho and Oregon water quality temperature standards.

Some stream segments were also listed for sediment, bacteria, and/or flow alteration. A review of the biological and chemical sediment data available showed no violations of applicable water quality standards for sediment and no impairment to the biological community from sediment. Therefore, TMDLs for sediment were not written; however, there can be no increase to the current sediment loads.

Bacteria was listed as a pollutant of concern for the North Fork Owyhee River, but sampling indicated bacteria levels did not violate current Idaho or Oregon standards, so a TMDL for bacteria was not written for the North Fork Owyhee River. Flow alteration was listed as a concern for several water bodies, but TMDLs were not prepared for flow alteration. Flow alteration is considered "pollution," but not a "pollutant," and 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.

Streams and Pollutants for Which TMDLs Were Developed

Middle Fork Owyhee River

Temperature

North Fork Owyhee River

Temperature

Big Spring Creek

Temperature

Cabin Creek

Temperature

Corral Creek

Temperature

Juniper Creek (two segments)

Temperature

Noon Creek

Temperature

Pleasant Valley Creek

Temperature

Squaw Creek (two segments)

Temperature

Subbasin Documents

• This subbasin assessment and TMDL document is not available electronically. To view a hard copy, contact DEQ's North and Middle Fork Owyhee River TMDL contact.
• Implementation Plan for the North and Middle Fork of the Owyhee River (February 2002)
• North and Middle Fork Owyhee River TMDL Five-Year Review (June 2009)