Clark Fork River-Silver Bow Creek Metals TMDL Project
Project Documents Project Outreach
The "Silver Bow Creek and Clark Fork River Metals TMDLs" document was approved by EPA in April 2014. The final document is available on the DEQ website at: http://deq.mt.gov/wqinfo/TMDL/finalReports.mcpx.
Project Purpose
The state of Montana monitors its waters and conducts water quality assessments to determine if waterbodies are supporting their designated uses. Waterbodies in the state of Montana have been classified to designate what beneficial uses they must support. The Clark Fork River below the Little Blackfoot River must be maintained suitable to support the uses of: agricultural, industrial, recreational, and drinking water uses, as well as support of fish and aquatic life. The Clark Fork River between the confluence of Silver Bow Creek and Warm Springs Creek and the mouth of the Little Blackfoot River does not have a drinking water use. Silver Bow Creek is an “I” classified water, which means that the goal of the State of Montana is for it to fully support all designated uses. Waters that are determined not to be supporting their designated uses are considered impaired and are placed on Montana’s list of impaired waters. Impaired waterbodies and their associated probable causes and sources of impairment are published within Montana’s biennial Water Quality Integrated Report.
Montana’s state law, and the federal Clean Water Act that was established by Congress in 1972, require development of total maximum daily loads (TMDLs) for all waterbodies impaired by a pollutant (e.g., metals, nutrients, sediment, temperature). A TMDL is the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards (think of a TMDL as a loading rate). TMDL development includes four main steps:
•Assessing the impaired waterbody’s existing water quality conditions and comparing those conditions to Montana’s water quality standards. During this step, measurable target values are set to help evaluate the stream’s condition in relation to the applicable water quality standards.
•Quantifying the amount of the pollutant contribution from each significant source
•Determining the total allowable load of the pollutant to the waterbody (i.e., the TMDL)
•Allocating the total allowable pollutant load into individual loads for each significant source (referred to as load allocations for nonpoint sources and wasteload allocations for point sources)
A TMDL document will be published for this project and will include information and results from each of these four steps. The document will also include recommended land management activities for improving water quality in this project area, and a monitoring strategy to evaluate progress toward attainment of water quality standards.
For more information about the development of TMDLs, please see the What is a TMDL? page on this site or download our pamphlet: Understanding the TMDL Process (580 kb).
Project Overview
[(Figure 1) Click map to enlarge]
The project area (Figure 1) includes Silver Bow Creek and the mainstem Clark Fork River from its start to the confluence with the Flathead River. Metals impairments for these waters have been re-assessed by DEQ’s Monitoring and Assessment program, and TMDL development reflects those reassessments. A number of metals impairments reported in the 2012 Integrated Report will be removed from the 2014 Integrated Report due to non-impairment, and several new metals impairments will be added. These are discussed below in the context of the individual streams. Stream reached for the project area are shown in (Figure 2).
Silver Bow Creek
Silver Bow Creek is currently an ‘I’ classified stream. Under this classification, the state’s goal is for the stream to support drinking water, aquatic life and all other uses. Therefore, TMDLs will be written for all metals impairment causes that impair any potential designated use: arsenic, cadmium, copper, lead, mercury and zinc.
Clark Fork River (Warm Springs Creek to Cottonwood Creek)
This reach of the Clark Fork River is a C-2 water. Therefore, drinking water is not a designated use, and the human health standard is not an impairment criterion. This reach of the river is determined to have metals impairment causes including: cadmium, copper, iron and lead.
Clark Fork River (Cottonwood Creek to Little Blackfoot River)
This reach of the Clark Fork River is a C-1 water. Therefore, drinking water is not a designated use, and the human health standard is not an impairment criterion. This reach of the river has metals impairment causes including: cadmium, copper, iron, lead and zinc.
Clark Fork River (Little Blackfoot River to Flint Creek) [(Figure 2) Click map to enlarge]
This reach of the Clark Fork River is a B-1 water (as are all downstream segments). Therefore, the drinking water beneficial use and human health standards apply to this segment, in addition to aquatic life criteria. This reach is determined to have metals impairment causes of: arsenic, cadmium, copper, iron and lead.
Clark Fork River (Flint Creek to Blackfoot River)
This reach of the Clark Fork River is a B-1 water. Therefore, the drinking water beneficial use and human health standards apply to this segment, in addition to aquatic life criteria. This reach is determined to have metals impairment causes of: arsenic, cadmium, copper, iron, lead and zinc.
Clark Fork River (Blackfoot River to Rattlesnake Creek)
This reach of the Clark Fork River is a B-1 water. Therefore, the drinking water beneficial use and human health standards apply to this segment, in addition to aquatic life criteria. This reach is determined to have metals impairment causes of: arsenic, cadmium, copper, iron, lead and zinc.
Clark Fork River (Rattlesnake Creek to Fish Creek)
This reach of the Clark Fork River is a B-1 water. Therefore, the drinking water beneficial use and human health standards apply to this segment, in addition to aquatic life criteria. This reach is determined to have metals impairment causes of: copper, iron, and lead.
Clark Fork River (Fish Creek to Flathead River)
This reach of the Clark Fork River is a B-1 water. Therefore, the drinking water beneficial use and human health standards apply to this segment, in addition to aquatic life criteria. This reach is determined to have metals impairment causes of: copper, iron, and lead.
As discussed above, the following metals TMDLs are being prepared for streams in the project area:
|
Stream |
Metals |
|
Silver Bow Creek |
Arsenic, cadmium, copper, lead, zinc, mercury |
|
Clark Fork River (Warm Springs to Cottonwood Creek) |
Cadmium, copper, iron, lead |
|
Clark Fork River (Cottonwood Creek to Little Blackfoot River) |
Cadmium, copper, iron, lead, zinc |
|
Clark Fork River (Little Blackfoot River to Flint Creek) |
Arsenic, cadmium, copper, iron, lead |
|
Clark Fork River (Flint Creek to Blackfoot River) |
Arsenic, cadmium, copper, iron, lead, zinc |
|
Clark Fork River (Blackfoot River to Rattlesnake Creek) |
Arsenic, cadmium, copper, iron, lead, zinc |
|
Clark Fork River (Rattlesnake Creek to Fish Creek) |
Copper, iron, lead |
|
Clark Fork River (Fish Creek to Flathead River) |
Copper, iron, lead |
Project Contacts
|
TMDLs |
Contact |
Agency |
|
Phone |
|
Project Coordinator |
Jordan Tollefson |
DEQ |
(406) 444-5341 |
|
|
Project Manager: Metals |
Eric Sivers | DEQ | esivers@mt.gov | (406) 444-0471 |
Page Released: September 27, 2013
Last Updated: July 7, 2014
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