Protecting Public Health and the Environment.

St. Joe River Subbasin

Subbasin at a Glance

Hydrologic Unit Code 17010304
Size 1,192 square miles (762,880 acres)

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

Alder Creek, Beaver Creek, Big Creek, Bluff Creek, Carpenter Creek, Charlie Creek, Crystal Creek, East and West Forks Bluff Creek, Emerald Creek, Fishhook Creek, Fly Creek, Gold Center Creek, Gold Creek, John Creek, Loop Creek, Marble Creek, Merry Creek, Mica Creek, Mosquito Creek, Renfro Creek, Santa Creek, Sherlock Creek, Simmons Creek, Slate Creek, St. Joe River, St. Maries River, Thorn Creek, Toles Creek, Tyson Creek, Upper and Lower Thorn Creeks, West and Middle Forks St. Maries River

Beneficial Uses Affected Cold water aquatic life, salmonid spawning, primary and secondary contact recreation
Major Land Uses Forestry, agriculture, recreation
Date St. Joe River Subbasin Assessment and TMDLs Approved by EPA

August 2003
EPA Approval Letter

Date St. Maries River Subbasin Assessment and TMDLs Approved by EPA

August 2003
EPA Approval Letter

Date St. Joe River Subbasin Addendum Approved by EPA

December 2011
EPA Approval Letter

Subbasin Characteristics

The St. Joe River subbasin is a large watershed composed of both the St. Joe River and the St. Maries River. The St. Joe River and its tributaries drain the entire watershed above the confluence with the St. Maries River at the city of St. Maries. The St. Maries River drains the western flank of the Clearwater Mountains, a subset of the Bitterroot Mountains. The river flows from the southeast to the northwest to enter the St. Joe River at the town of St. Maries.

2003 Subbasin Assessment and TMDL

In the St. Joe River drainage, 14 of the 17 listed segments are listed for temperature, 11 for sediment, 5 for bacteria, 3 for dissolved oxygen, and 1 segment each for nutrients and habitat alteration. In the St. Maries River drainage, 16 of the 17 listed segments are listed for sediment, 9 for temperature, 8 for habitat alteration, 4 for nutrients, and 1 each for dissolved oxygen and bacteria. Sediment originates in the basin primarily from eroding banks, road crossings, and encroachments. Temperature is most affected by stream shading. Nutrients and bacteria arise from livestock and human wastes, while dissolved oxygen is affected by discharge of oxygen-demanding materials from wastewater treatment facilities and livestock wastes.

Impairment of the cold water beneficial use was assessed using composite scores of fish, macroinvertebrate, and habitat indices. These scores generally indicated full support in most streams assessed in the St. Joe River drainage, but they also indicated use impairment in some tributaries to the St. Joe River. The St. Joe River itself was not listed, nor was it found to be impaired in this assessment. In the St. Maries River drainage, the scores generally indicated full support in the headwaters but revealed use impairment in the downstream reaches of both the tributaries and the river itself.

The assessment resulted in temperature TMDLs for all the segments listed for temperature. Sediment TMDLs were completed for Mica, Fishhook, Bear, and Little Bear Creeks in the St. Joe River drainage; in the St. Maries River drainage, sediment TMDLs were developed for St. Maries River, West Fork St. Maries River, Middle Fork St. Maries River, and Santa, Carpenter, Emerald, Alder, Tyson, Thorn, Renfro, Crystal, Charlie, and John Creeks. Recommendations were also made for delisting certain streams and pollutants.

The US Environmental Protection Agency considers certain unnatural conditions, including habitat alteration, that are not the result of the discharge of a specific pollutant as "pollution." Since a TMDL is not required for a water body impaired by pollution, but not a specific pollutant, a TMDL was not developed for habitat alteration.

2003 TMDL: Streams and Pollutants for Which TMDLs Were Developed

St. Joe River Drainage

Bear Creek
Sediment, temperature
Beaver Creek
Temperature
Blackjack Creek
Temperature
Bluff Creek
Temperature
Fishhook Creek
Sediment, temperature
Fly Creek
Temperature
Gold Creek
Temperature
Harvey Creek
Temperature
Heller Creek
Temperature
Little Bear Creek
Sediment, temperature
Loop Creek
Temperature
Mica Creek
Sediment
Mosquito Creek
Temperature
Simmons Creek
Temperature
Tank Creek
Temperature

St. Maries River Drainage

St. Maries River (2 segments)
Sediment, temperature
West Fork St. Maries River
Sediment, temperature
Middle Fork St. Maries River
Sediment, temperature
Santa Creek
Sediment, temperature
Carpenter Creek
Sediment
Emerald Creek
Sediment, temperature
Gold Center Creek
Temperature
Flewsie Creek
Temperature
Alder Creek
Sediment
Tyson Creek
Sediment
Thorn Creek
Sediment
Renfro Creek
Sediment
Crystal Creek
Sediment
Charlie Creek
Sediment
John Creek
Sediment
Gramp Creek
Temperature

2011 Addendum

Within the St. Joe River subbasin, water temperature standards were exceeded in 16 assessment units (AUs) in the St. Joe River watershed and 18 AUs in the St. Maries River watershed. TMDLs were developed for these 34 AUs in 2003. Following the US Environmental Protection Agency’s approval of the TMDLs in 2003, 15 additional AUs were assessed and determined to be exceeding Idaho water quality temperature standards.

This document reviews water bodies in the St. Joe River subbasin that were addressed in the 2003 TMDLs and streams that were identified as exceeding Idaho water quality temperature standards following the completion of TMDLs in 2003. AUs addressed by an EPA-approved TMDL are reevaluated in this analysis because of new techniques in temperature TMDL development. TMDLs developed in 2003 relied on a mathematical equation to prescribe shade based on elevation to achieve a desired stream temperature. Due to the elevation of the watersheds analyzed, the shade requirements in most locations exceeded 100%. Complete stream shade is not achievable in a natural setting, so those streams addressed by the 2003 TMDLs were reevaluated in this document using potential natural vegetation (PNV) methods.

2011 Addendum: Streams and Pollutant for Which TMDLs Were Developed

Big Creek and East Fork Big Creek
Temperature
Heller and Sherlock Creeks
Temperature
John Creek
Temperature
Tyson Creek
Temperature
Carpenter Creek
Temperature
Merry Creek
Temperature
Thorn Creek
Temperature

Subbasin Documents


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