Protecting Public Health and the Environment.

Pend Oreille Lake Subbasin

Subbasin at a Glance

Hydrologic Unit Code 17010214
Size 70 square miles (44,740 acres)

Water Bodies with EPA-Approved TMDLs (Category 4a)

Berry Creek, Caribou Creek, Cedar Creek, Cheer Creek, Chloride Creek, Chloride Gulch, Cocolalla Creek, Cocolalla Lake, Colburn Creek, Fish Creek, Gold Creek, Granite Creek, Grouse Creek, Hellroaring Creek, Hoodoo Creek, Jeru Creek, Little Sand Creek, McCormick Creek, North Fork Grouse Creek, Pend Oreille Lake, Rapid Lightning Creek, Sand Creek, Schweitzer Creek, Spring Jack Creek, Swede Creek, Trestle Creek, Trout Creek, Upper and Lower Pack River, West and North Gold Creeks

Beneficial Uses Affected Water supply, recreation, salmonid spawning, cold water aquatic life, wildlife habitat, aesthetics
Major Land Uses Forestry, urban, shrubland, wetland, pasture/cropland
Date Approved by EPA

October 2002
EPA Approval Letter

Dates Clark Fork-Pend Oreille TMDL Approved by EPA

April 2001
EPA Approval Letter

September 2000
EPA Approval Letter

Date Temperature TMDL Addendum Approved by EPA April 2008
EPA Approval Letter
Date Sediment TMDL Addendum Approved by EPA January 2008
EPA Approval Letter
Date Pack River Nutrients TMDL Addendum Approved by EPA December 2008
EPA Approval Letter

Subbasin Characteristics

Lake Pend Oreille is part of the Clark Fork-Pend Oreille Basin, which lies in western Montana, northern Idaho, and northeastern Washington. The Clark Fork River begins near Butte, Montana, and drains an extensive area of western Montana before entering Lake Pend Oreille in Idaho at the lake's northeast corner. The lake is the source of the Pend Oreille River in northeastern Washington, which ultimately drains to the Columbia River.

2002 Subbasin Assessment and TMDL

Lake Pend Oreille was placed on Idaho's 1994 §303(d) list as a "threatened" water body and retained on the 1996 and 1998 lists. Because of this listing, DEQ prepared a problem assessment for the lake, which recommended developing a TMDL for the nearshore waters of the lake to mitigate increasing eutrophication along the shoreline. This TMDL addresses this recommendation.

2002 TMDL: Streams and Pollutant for Which TMDLs Were Developed

Nearshore waters of Lake Pend Oreille
Total phosphorus

2001 Clark Fork–Pend Oreille Watershed Assessment and TMDL

This watershed spans two subbasins and is summarized in the table below.

Hydrologic Unit Codes 17010213 (Lower Clark Fork Subbasin)
17010214 (Pend Oreille Lake Subbasin)
Size 25,000 square miles (16,000,000 acres) in Idaho and Montana
Beneficial Uses Affected Cold water aquatic life, salmonid spawning, warm water biota, primary contact recreation, secondary contact recreation, agricultural water supply, industrial water supply, domestic water supply

Major Land Uses

Agriculture, grazing, roads, hydropower, mining, timber harvest, urban, recreation

* These water bodies are located in the Lower Clark Fork subbasin (hydrologic unit code 17010213). They are analyzed in the Clark Fork/Pend Oreille subbasin assessment document and are assigned TMDLs in the Lower Clark Fork River Subbasin Assessment and Total Maximum Daily Loads developed in 2007.

The Clark Fork-Pend Oreille watershed lies in western Montana, northern Idaho, and northeastern Washington. The watershed is the source of the water that enters and leaves Lake Pend Oreille, the largest and deepest natural lake in Idaho. Inflow and outflow of the lake are regulated by hydroelectric facilities.

The Pend Oreille portion of this subbasin assessment examined 11 streams, 1 major river, and 2 lakes. Of the 11 streams, 5 were water quality impaired and required load allocations, primarily for sediment. Both Lake Pend Oreille and the Pend Oreille River were found to fully support their beneficial uses and were recommended for delisting.

The Clark Fork portion of this subbasin assessment was tabled until its scheduled assessment date in 2004. Insufficient time to complete the assessment and the prospect of more data available at that time drove this decision.

2001 TMDL: Streams and Pollutants for Which TMDLs Were Developed

Cocolalla Creek (lower)
Sediment
Cocolalla Creek (upper)
Sediment
North Fork Grouse Creek
Sediment
Hoodoo Creek
Sediment
Pack River
Sediment
Cocolalla Lake
Phosphorus

2007 Clark Fork - Pend Oreille Addendum: Nutrients

This document addresses streams in the Pack River watershed that have been placed on Idaho’s §303(d) list. This document only addresses nutrient impairments for the Pack River watershed, which is located in the Pend Oreille Lake subbasin in northern Idaho. The Pack River watershed encompasses approximately 185,600 acres.

The Pack River and its tributaries have been identified as impaired due to causes unknown. Stressor identification reports were completed for all assessment units impaired by causes unknown, and potential stressors/pollutants have been identified for each assessment unit. For each assessment unit the following stressors/pollutants were evaluated as possible contributors to impairment: low nutrients, altered flow regime, increased sediment, reduction in riparian habitat, increased metals concentrations, increased nutrients, and misuse of sampling protocol. Stressor identification reports shows sediment, temperature, and nutrients as the likely pollutants. During this addendum effort, DEQ developed nutrient TMDLs for four water bodies (ten assessment units).

2007 Addendum (Nutrients): Streams and Pollutants for Which TMDLs Were Developed

Sand Creek
Nutrients
Colburn Creek
Nutrients
Trout Creek
Nutrients
Pack River
Nutrients

2007 Clark Fork - Pend Oreille Addendum: Temperature

This addendum addresses 19 water bodies in the Pend Oreille Lake subbasin placed on Idaho’s §303(d) list for temperature impairment. Effective shade targets were established for these streams 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 the Northwest. Existing shade was determined from aerial photo interpretation field verified with a Solar Pathfinder.

Most streams examined in this TMDL had excess solar loads. Notably, the Pack River and several of its larger tributaries (Grouse Creek, Rapid Lightning Creek, McCormick Creek, and Hellroaring Creek) had high excess loads with reductions of 30% to 90% necessary to achieve target levels. Hoodoo Creek and upper Cocolalla Creek also had high excess loads; however, their necessary percent reductions were generally less than 30%. North Fork Grouse Creek and Granite Creek are recommended for delisting from the §303(d) list for temperature based on analysis performed while developing these TMDLs.

2007 Addendum (Temperature): Streams and Pollutants for Which TMDLs Were Developed

Hoodoo Creek
Temperature
Cocolalla Creek
Temperature
Fish Creek
Temperature
Granite Creek
Temperature
Grouse Creek
Temperature
Pack River
Temperature
Trestle Creek
Temperature
Cedar Creek
Temperature
"South" Gold Creek
Temperature
West Gold Creek
Temperature
Chloride Gulch Creek
Temperature
Hellroaring Creek
Temperature
Jeru Creek
Temperature
McCormick Creek
Temperature
North Fork Grouse Creek
Temperature
North Gold Creek
Temperature
Rapid Lightening Creek
Temperature
"West" Sand Creek
Temperature
Trout Creek
Temperature

2007 Clark Fork - Pend Oreille Addendum: Sediment

The overall purpose of this addendum is to characterize and document sediment pollutant loads for a select group of tributaries in the Pend Oreille Lake subbasin. This report addresses five watersheds in the Pend Oreille Subbasin that include 11 assessment units identified in Idaho’s 2002 Integrated Report as water quality limited by an unknown pollutant or excess sediment. These 6th-order watersheds are Upper Pack Creek, Gold Creek, North Gold Creek, Rapid Lightning Creek, and Sand Creek. The five watersheds addressed in this report comprise 121,927 acres, or approximately 190 square miles of the Pend Oreille Lake subbasin, and include assessment units encompassing the Pack River, McCormick Creek, HellroaringCreek, Sand Creek, Schweitzer Creek, Gold Creek, Rapid Lightning Creek, and North Gold Creek. Sediment TMDLs were established for 14 assessment units to reduce nonpoint source sediment pollutant loads in the subbasin.

2007 Addendum (Sediment): Streams and Pollutants for Which TMDLs Were Developed

Upper Pack River
Sediment
Hellroaring Creek
Sediment
Sand Creek
Sediment
Jack Creek
Sediment
Swede Creek
Sediment
Schweitzer Creek
Sediment
Little Sand Creek
Sediment
Gold Creek
Sediment
North Gold Creek
Sediment

Subbasin Documents


Staff Contacts

TMDL Technical Lead
Robert Steed
DEQ Coeur d'Alene Regional Office
2110 Ironwood Parkway
Coeur d'Alene, ID 83814
(208) 769-1422
robert.steed@deq.idaho.gov