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Tongue River Watershed Monitoring and Assessment

Page history last edited by Christina Staten 4 weeks ago Saved with comment

 


Tongue River Home Page          Salinity Model          TMDL Development

 

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Page Contents



 

Water Quality Monitoring and Assessment in Montana

Montana DEQ performs water quality assessments to determine whether a waterbody is impaired. An impairment means that the waterbody is not meeting Montana's water quality standards for the pollutant being assessed (e.g., iron, salinity, sediment, temperature) because one or more of the waterbody's water quality beneficial uses (support of: agricultural uses, aquatic life, human recreation, and/or drinking water) are limited or harmed to some extent. Waterbodies that have been monitored by DEQ are also referred to as "assessment units." Assessment units can be the full length of a stream or the full extent of a lake or reservoir (such as Otter Creek and the Tongue River Reservoir shown in the table below), or they may be a portion of a lake or stream (a stream segment). Montana DEQ may choose to break streams into multiple segments, determined by a variety of factors, such as stream length for very long streams. The Montana portion of the Tongue River is divided into seven waterbody segments, or assessment units (see table below).  

 

Tongue River Watershed Water Quality Assessment Information

The table below contains all of the waterbodies in the Montana portion of the Tongue River watershed that have been assessed by Montana DEQ, and lists the pollutants for which the waterbody was determined to be impaired. Not all waterbodies in the Tongue River watershed have been sampled/monitored; therefore, we do not know whether their water quality beneficial uses are being fully supported and if they are meeting Montana's water quality standards. However, water quality monitoring has been conducted on additional tributaries of the Tongue River not shown in the below table, but DEQ has insufficient data to assess whether they meet water quality standards.  

 

Click on waterbody names/assessment units in the table to view summaries of their water quality assessments; full, detailed assessment reports can be accessed from the top of the summary pages. 

 

Waterbody Segment (Assessment Unit)

(Click Name to View Assessment Record)

Assessment Unit ID

County

Probable Impairment Causes (2020)1

Tongue River

Tongue River

Wyoming border to Wyoming border

MT42B001_011

Big Horn

None identified

Tongue River

Wyoming border to Tongue River Reservoir

MT42B001_010

Big Horn

Iron

Flow regime modification

Tongue River

Tongue River Dam to Prairie Dog Creek

MT42B001_020

Big Horn,

Rosebud

Flow regime modification

Tongue River

Prairie Dog Creek to Hanging Woman Creek

MT42B001_021

Rosebud

Flow regime modification

Tongue River

Hanging Woman Creek to Beaver Creek

MT42C001_013

Rosebud

Iron

Flow regime modifications

Sediment

Tongue River

Beaver Creek to Twelve Mile Dam, T6N, R48E, S29

MT42C001_014

Rosebud,

Custer

Iron

Flow regime modifications

Sediment

Specific Conductivity

Tongue River

Twelve Mile Dam to mouth (Yellowstone River)

MT42C001_011

Custer

Cadmium

Copper

Iron

Lead

Flow regime modification

Nickel

Salinity

Sediment

Zinc

Tongue River Reservoir

Tongue River Reservoir

MT42B003_010

Big Horn

Chlorophyll-a

Dissolved oxygen

Sediment

Tongue River Tributaries

Hanging Woman Creek

Wyoming border to Stroud Creek

MT42B002_032

Big Horn,

Rosebud

Salinity

Flow regime modification

Hanging Woman Creek

Stroud Creek to mouth (Tongue River)

MT42B002_031

Rosebud

Iron

Salinity

Sedimentation-Siltation

Flow regime modification

Otter Creek 2

Headwaters to mouth (Tongue River)

MT42C002_020

Powder River,

Rosebud

Iron

Salinity

Alteration in streamside or littoral vegetative covers

Pumpkin Creek

Headwaters to Little Pumpkin Creek

MT42C002_061

Powder River

Salinity

Temperature

Flow regime modification

Pumpkin Creek

Little Pumpkin Creek to the mouth (Tongue River)

MT42C002_062

Powder River,

Custer

Salinity

Temperature

Flow regime modification

1 Impairment causes identified in Montana’s 2020 Water Quality Integrated Report

2 A draft iron TMDL document has been completed; site-specific salinity standards for Otter Creek are under development. See the Otter Creek pages for additional information.

  

New Assessments Taking Place in the Tongue River Watershed

In 2019, Montana DEQ re-assessed the segment of the Tongue River between Beaver Creek and the Twelve Mile Dam (assessment unit MT42C001_014) to determine whether it is impaired for salinity, and has listed this segment as impaired for specific conductivity on the 2020 list of impaired waters.

 

Montana's Salinity Water Quality Standards

Montana uses electrical conductivity (EC) and sodium adsorption ratio (SAR) as measurements of salinity. Numeric water quality standards are established for these two parameters; however, if a waterbody does not meet these water quality standards, it is determined to be impaired for "salinity" and placed on the list of impaired waters. EC and SAR water quality standards for the Tongue River are:

 

From November 1 through March 1, the monthly average standard for EC is 1,500 microsiemens per centimeter (µS/cm) and no sample may exceed an EC value of 2,500 µS/cm. The monthly average standard for SAR is 5.0 and no sample may exceed a SAR value of 7.5.

 

From March 2 through October 31, the monthly average standard for EC is 1,000 µS/cm and no sample may exceed an EC value of 1,500 µS/cm. The monthly average standard for SAR is 3.0 and no sample may exceed a SAR value of 4.5.

 

Data Used for Salinity Assessments and in the Tongue River Salinity Model

All of the water quality and flow data used by Montana DEQ is available in either the National Water Quality Portal that is maintained by the U.S. Environmental Protection Agency, or the U.S. Geological Survey's (USGS) NWIS database for Montana. The National Water Quality Portal contains data collected by Montana DEQ, volunteer monitoring groups, the U.S. Geological Survey (USGS), as well as other data collection entities. The USGS's Water Quality Data for Montana website (NWIS) provides data downloads for both daily flow and water quality data collected at USGS gages and for laboratory-analyzed samples collected by the USGS. 

 

Additional information on the sources of data being used for the Tongue River salinity water quality model is contained on the Salinity Model page.  

 

 

Tongue River Project Contacts

 

Role

DEQ Contact

Email

Phone

Project Coordinator

Christina Staten

CStaten@mt.gov

(406) 444-2836

Project Modeler*

Eric Regensburger

ERegensburger@mt.gov

(406) 444-6714

Salinity TMDL Project Manager

Christy Meredith

Christy.Meredith@mt.gov

(406) 444-6824

Tongue River Salinity Assessment Darrin Kron DKron@mt.gov (406) 444-4765

* The project modeler changed from Erik Makus to Eric Regensburger in January 2019

 


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Page Released: July 6, 2016

Last Updated: October 1, 2020