Department of
Environmental Quality

Subbasin at a Glance

Overview

The South Fork Payette River near Lowman, Idaho, flows generally from east to west from its origin in the west slopes of the Sawtooth Mountains to its confluence with the Middle Fork Payette River near Garden Valley. From the Sawtooth Wilderness Area boundary to the confluence of the Middle Fork Payette River, the South Fork Payette River is listed on the 1998 §303(d) list for fine-grained sediment.

The subbasin contains bull trout, a species listed as threatened under the Endangered Species Act. The South Fork Payette River is a key bull trout watershed in Idaho. Fine-grained sediment is one of the factors identified as limiting bull trout habitat.

Suspended sediment data for the South Fork Payette River show that during years of normal flow, the water column sediment levels are well below the suspended sediment target; however, during years of high flow, when erosion can be significant, the sediment target is exceeded.

DEQ does not recommend developing a sediment TMDL for the South Fork Payette River and recommends de-listing the segment from the §303(d) list. However, because anthropogenic sources of sediment (primarily from forest roads) exist within the basin and exceedances of the target are documented in high flow years, road management activities should be prioritized to reduce erosion.

Summary of Assessment Outcomes

The segment of the South Fork Payette River extending from the wilderness boundary to the Middle Fork Payette River is proposed for delisting during the next §303(d)-listing cycle. Four unlisted creeks in the subbasin (Wash Creek, Chapman Creek, Horn Creek, and Smokey Creek) show impairment; however, naturally occurring events are in all likelihood the major causes of this impairment. It is recommended that monitoring continue on these streams.

Subbasin Documents

• South Fork Payette River Subbasin Assessment (July 2005)
• South Fork Payette River Subbasin Five-Year Review (January 2011)