Department of
Environmental Quality

Subbasin at a Glance

Overview

The South Fork Owyhee River is located in the far southwestern portion of Idaho and originates in the north central portion of Nevada. The area is predominately open desert and deep canyons.

The hydrology of the South Fork Owyhee River is the river itself. There are no perennial streams that feed the river within Idaho. The South Fork Owyhee River is subject to “flashy” flow conditions with peak flows occurring anytime from January to June. There are no major impoundments in either Nevada or Idaho.

With the exception of temperature, water column chemistry meets the Idaho Water Quality Standards and Wastewater Treatment Requirements. Water temperatures often exceed water quality standards for the protection of both cold water biota and salmonid spawning. Warm water temperatures may be the most important factor limiting the presence of trout species. There is no indication that sediments are impairing beneficial uses.

A TMDL for temperature is an appropriate vehicle for addressing temperature concerns in the South Fork Owyhee River. A load capacity is assigned in this document, which includes a load allocation for the water as it enters the state of Idaho.

If the South Fork Owyhee River is able to meet Idaho temperature criteria at the Idaho/Nevada border, the argument could be made that the additional increase in Idaho is natural, and site-specific criteria could be developed. Alternatively, if the South Fork Owyhee River cannot meet Idaho temperature criteria at the border, then Idaho and Nevada will need to work together to develop appropriate site-specific criteria.

Stream and Pollutant for Which TMDLs Were Developed

S. Fork Owyhee River

Temperature

Subbasin Document

• South Fork Owyhee River Subbasin Assessment and Total Maximum Daily Load (December 1999)