Official Government Website

Payette River Subbasin

Data Details
Hydrologic Unit Code 17050122
Size 594 square miles (380,000 acres)
Water Bodies with EPA-Approved TMDLs (Category 4a) Big Willow Creek, Bissel Creek, Dry Creek, Little Willow Creek, Payette River
Beneficial Uses Affected Cold water aquatic life, primary contact recreation, secondary contact recreation, salmonid spawning
Major Land Uses Rangeland, irrigated agriculture
Approved by EPA May 2000
Bissel Creek TMDL Approved by EPA October 2003
Big Willow Addendum Approved by EPA July 2008 EPA Approval Letter
Little Willow Addendum Approved by EPA December 2013 EPA Approval Letter
Payette River Subbasin Approved by EPA October 2021 EPA Approval Letter

Subbasin Characteristics

The lower Payette River is located in southwestern Idaho. Bissel Creek, also listed on the 1994 §303(d) list and located in the lower Payette River subbasin, is addressed in a separate document, discussed below.

The hydrology of the river is complex, with numerous irrigation water withdrawal and return drains dominating both the flow and quality of the river. Black Canyon Dam has greatly altered the amount and type of sediment in the lower Payette River originating from the upper watershed.

1999 Subbasin Assessment and TMDL

Fisheries studies conducted by the Idaho Department of Fish and Game in 1997 indicate many of the same species supported by the river in 1974 were also supported in 1997. Mountain Whitefish is the dominant coldwater species. Warmwater species can be found throughout the river, with nongame species being dominant.

Sources of pollutants include both point sources and nonpoint sources. Point sources are limited mainly to municipal wastewater treatment plants and confined animal feeding operations. Nonpoint sources are associated with agricultural, urban, suburban, and rural areas.

Nutrients have not been shown to cause impairment to the beneficial uses in this water body at this time. While total phosphorus and nitrogen are at concentrations that could cause nuisance aquatic vegetation growth, data show they do not, most likely due to sufficient water flow. If it is determined that the lower Payette River is a significant source of nutrients to the lower Snake River (in the lower Snake River/Brownlee TMDL), reduction targets for the lower Payette River will be addressed at that time.

Summer water temperatures in the lower Payette River are warm and exceed water quality standards for both cold water biota and salmonid spawning. However, it was determined that other factors, including habitat modification and flow alteration, were also significant causes of beneficial use impairment. In addition, warm water temperatures that exceed water quality standards originate from Black Canyon Reservoir. Because of these conditions, a temperature TMDL was not developed during this original TMDL effort. TMDLs were also not written for flow alteration and habitat modification because these are not pollutants as described under Section 303(d) of the Clean Water Act.

Fecal coliform bacteria levels exceed the water quality standards for both primary and secondary contact recreation. Increasing levels are noted from Black Canyon Dam to the Snake River, with an exceedance of the water quality standards from river mile 25 to the confluence. Overall, a fecal coliform reduction of 84% will be required to achieve water quality standards. The load allocation will focus on nonpoint sources only. The overall contribution to the fecal coliform bacteria load from point sources (municipal wastewater treatment plants) is 0.005%. If the total elimination of bacteria from the point sources were to occur, a total load reduction of only 0.07% would be achieved. Therefore, any reduction from point sources would not impact the overall load to the lower Payette River.

2003 Bissel Creek Watershed Assessment and TMDL

Bissel Creek is a 15.3-mile 2nd-order tributary to the lower Payette River in Gem County, Idaho. TMDLs for the rest of the Lower Payette River subbasin are addressed in a separate document. The confluence of Bissel Creek and the lower Payette River is located approximately 11 miles downstream and west of Emmett at Letha. Landownership within the Bissel Creek drainage includes both private and public lands. Much of the public land is managed for grazing by the Bureau of Land Management. The Bissel Creek watershed is approximately 25.5 square miles (16,297 acres).

In 1998, Bissel Creek was classified as water quality limited due to excessive sediment. In addition, recent bacteria data obtained for Bissel Creek indicate that primary contact recreation is not supported. Data indicate that below the North Side Canal, Bissel Creek contains excess total suspended solids during the irrigation season (April – September). The irrigation season total suspended solids average at two of the three established monitoring locations exceeds the 22 milligrams per liter target. A total suspended solids TMDL was developed in this document for the segment below the North Side Canal to reduce the amount of sediment in the water column.

The data also indicate that Bissel Creek contains excess E. coli bacteria below the North Side Canal. Estimated geometric mean concentrations for the month of July at all three established monitoring locations show that the E. coli concentration is more than five times the standard of 126 organisms per 100 milliliters of water. At one location, the concentration is more than seven times the standard. A TMDL was developed in this document to reduce the amount of E. coli bacteria in the stream.

2003 TMDL: Stream and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Bissel Creek Sediment, bacteria

2005 Payette River and North Fork Payette River Watershed Assessment and TMDL

Watershed at a Glance

This watershed spans two subbasins, as summarized in the table below.

Hydrologic Unit Codes17050122 (Payette) and 17050123 (North Fork Payette)
Size2,152 square miles (1,377,280 acres)
Beneficial Uses AffectedCold water aquatic life, salmonid spawning, primary contact recreation, domestic water supply
Major Land UsesAgriculture, forest, range, municipalities

The Payette River watershed lies entirely in southwestern Idaho and comprises about 3,240 square miles in two different subbasins. The drainage originates in the Sawtooth and Salmon River Mountains and flows southwesterly until it empties into the Snake River near Payette, Idaho.

This TMDL lies within parts of two hydrologic units and encompasses several geographically distinct subwatersheds. This TMDL addresses §303(d)-listed tributaries to the North Fork Payette River above Payette Lake and to Payette Lake itself; the North Fork Payette River and tributaries from Cascade Dam to the confluence with the South Fork Payette River; and the main stem Payette River up to and including Black Canyon Reservoir.

The North Fork Payette River is listed for nutrients, sediment, and temperature. Beneficial uses are not impaired by nutrients, so nutrients are recommended for delisting. Temperatures exceed the temperature standard, primarily due to warm water exiting Cascade Reservoir. Canopy cover meets target levels, so a TMDL was not developed for temperature. A TMDL for sediment was developed.

Big Creek is listed as impaired by sediment and data show that beneficial uses are impaired. Banks are stable in some sections but actively eroding in others. A TMDL was developed for sediment. In Round Valley Creek, beneficial uses are impaired due to excess sediment from instream channel erosion. A TMDL was developed.

Temperature TMDLs were developed for Box Creek and Fall Creek in order to achieve salmonid spawning criteria. The streams support beneficial uses but do not meet the salmonid spawning standard.

Beneficial uses are not supported in the lower reach of Clear Creek due to excess sediment from upstream and instream channel erosion. In the upper reaches of Clear Creek, beneficial uses are fully supported but are threatened due to excess sediment. A sediment TMDL was set for the upper watershed to improve habitat in the lower reaches.

Browns Pond is listed for habitat alteration. However, habitat alteration is not considered a “pollutant,” and TMDLs are not required for pollution that is not caused by a pollutant. Therefore, a TMDL for Browns Pond was not developed.

Soldier Creek is listed for sediment. DEQ proposes delisting Soldier Creek from the headwaters to the confluence with North Fork Soldier Creek but leaving the lower section of Soldier Creek on the §303(d) list. DEQ will use data gathered in 2005 to determine whether sediment is impairing beneficial uses in the lower section. Tripod Creek was preliminarily found to be unimpaired and a TMDL is not recommended at this time. Additional monitoring data will become available in 2005, which may result in further study of Tripod Creek and TMDL development.

It is proposed that Brush Creek, Elip Creek, and Landing Creek be removed from the §303(d) list and that Black Canyon Reservoir be delisted for nutrients, sediment, and oil and grease but listed for habitat alteration. It is also proposed that Squaw Creek be added to the next §303(d) list for bacteria and nutrients.

2005 TMDL: Streams and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Big Creek Sediment
Box Creek Temperature
Clear Creek Sediment
Fall Creek Temperature
Round Valley Creek Sediment
North Fork Payette River Sediment

2008 Addendum

This document addresses assessment units (AUs) in the Big Willow Creek watershed and develops a TMDL for temperature for listed AUs using potential natural vegetation (PNV) targets. Effective shade targets were established for Big Willow Creek based on the concept that maximum shading under PNV equals natural background temperature levels. Shade targets were derived from effective shade curves developed for similar vegetation types in the Northwest. Existing shade was estimated from aerial photo interpretation and field-verified with Solar Pathfinder data.

2008 Addendum: Stream and Pollutant for Which TMDLs Were Developed

Stream Pollutants
Big Willow Creek Temperature

2013 Addendum

Little Willow Creek is a watershed located within the lower Payette River subbasin and is a tributary of the Payette River. This document presents an addendum to the 1999 Lower Payette River subbasin assessment and TMDL and addresses the water bodies in the Little Willow Creek watershed that are on Idaho’s 2010 §303(d) list along with two unlisted pollutants causing water quality impairment.

In 2010, DEQ completed a 5-year review of the original lower Payette River TMDL that indicated the beneficial uses of Little Willow Creek were impaired. In 2007, the Idaho State Department of Agriculture (ISDA) collected suspended sediment concentration data, E. coli data, and stream temperature data that indicated beneficial uses were impaired in Little Willow Creek. In 2012, DEQ collected additional E. coli and temperature data from Little Willow Creek, confirming contact recreation and cold water aquatic life beneficial uses were impaired. E. coli levels in Little Willow Creek exceeded Idaho “Water Quality Standards” (IDAPA 58.01.02) for contact recreation. Temperature also exceeded water quality standards for cold water aquatic life. Both cold water aquatic life and contact recreation are impacted by nonpoint source pollutants.

Effective target shade levels were established for two assessment units based on the concept of maximum shading under potential natural vegetation resulting in natural background temperature levels. Shade targets were derived from effective shade curves developed for similar vegetation types in Idaho. Existing shade was determined from aerial photo interpretation that was partially field verified with Solar Pathfinder data. Target and existing shade levels were compared to determine the amount of shade needed to bring water bodies into compliance with temperature criteria in IDAPA 58.01.02.

TMDLs were developed for two assessment units on Little Willow Creek: one had three TMDLs developed (sediment, E. coli, and temperature) while the other had only a temperature TMDL developed.

2013 Addendum: Stream and Pollutants for Which TMDLs Were Developed

Stream Pollutants
Big Willow Creek Temperature

2021 Payette Subbasin E. Coli TMDLs

Three assessment units within the Payette subbasin were identified as not supporting primary or secondary contact recreation beneficial uses due to exceedances of numeric E. coli criteria. This document established bacteria (E. coli TMDLs for three assessment units that are impacted by non-point sources pollution. The TMDL analysis established water quality targets, load capacities, estimates of existing pollutants loads, and estimated load reduction needed to protect water quality standards.

2021 TMDL: Streams and Pollutants for Which TMDLs were Developed

Stream Pollutants
Tributaries to Black Canyon Reservoir E. coli
Dry Buck and Peterson, & Fleming Creeks 1st & 2nd order E. coli
Sand Hollow – 3rd order E. coli

Subbasin Document(s)

This accordion will not appear on the screen

DEQ Boise Regional Office
1445 N. Orchard St.
Boise, ID 83706
Ph: (208) 373-0550
Fax: (208) 373-0287
Toll Free: (888) 800-3480

ver: 3.5.2 | last updated:
Jump back to top of page button