Montana Department of Environmental Quality About Us Permitting & Operator Assistance Public Participation



Supplementary resources including documents, reports, frequently asked questions, and guidance. For additional information please visit the specific DEQ program page. To obtain records that are not available on the DEQ website please visit the Public Records Center.

New!  Water - Advisory Council page

Water Quality Library

The Water Quality Library was formed to support the mission and operations of the Montana DEQ's Water Quality Division by making water quality documents and publications available to the public. There are over 8,500 titles in the collection including books, reports, journal articles, and DVDs, covering subjects related to water quality including methodology, toxicology, soils, mining, nonpoint pollution, fish, forestry, and modeling.

Search Water Quality Library

Clean Water Act Information Center (CWAIC)

Here you will find information about the quality of Montana's rivers, streams, and lakes in relation to Montana's Water Quality assessments. These assessments are derived from available statewide water monitoring data and information. The Clean Water Act Information Center also provides access to Montana's Water Quality Reports and List of Impaired Surface Waters, as well as online search and mapping tools.

Search Water Quality Assessment Information

The federal Clean Water Act requires DEQ to assess Montana’s water quality and prepare a report every two years. The Montana Water Quality Report and List of Impaired Waters (known as the Integrated Report) combines reporting information for the Clean Water Act Section 305(b) assessment of water bodies and the Section 303(d) list of water bodies that do not meet water quality standards. Water bodies not meeting standards need pollution reduction studies, called Total Maximum Daily Loads (TMDLs). TMDLs also include plans to improve water quality to eventually meet standards.

When assessing surface water quality in Montana, DEQ is guided by the Beneficial Use Assessment Method for Montana’s Surface Waters. This document describes the framework used to assess state waters and to make the beneficial use support and water quality impairment decisions that are presented in the Water Quality Integrated Report.

DEQ assesses whether state surface waters are meeting applicable water quality standards for specific water quality characteristics, or parameters. If a waterbody is not meeting one or more water quality standards, DEQ considers the waterbody impaired and adds it to Montana’s list of impaired waters in the Water Quality Integrated Report. DEQ develops parameter-specific assessment methods which present the required data, analyses, and decision frameworks used to make these parameter-specific impairment listing decisions.

These documents and supporting files constitute the State of Montana's final Water Quality Integrated Report submission to the U.S. EPA for the given reporting cycle. This includes both the Section 303(d) List and Section 305(b) Report as required under the federal Clean Water Act.

Sign Up to Receive Email Updates

Montana classifies its waterbodies according to present and future beneficial uses they are expected to support (§ 75-5-301, MCA). This layer displays surface water bodies in Montana contained the NHD and their associated use class.

Go To The Use Class Map

Montana’s surface-water-use classification system bases class assignments primarily on water temperature, fish, and associated aquatic life. Each class has an associated beneficial use. A waterbody supports its beneficial uses when it meets the Water Quality Standards (WQS) established to protect those uses. A waterbody is impaired when any one of its WQS are violated.

Determining whether or not a specific use is supported is independent of all other designated uses. For example, a waterbody may partially support aquatic life because of excess nutrients, not support drinking water because of arsenic, but fully support agriculture and industrial uses. Classes A, B, and C are the three most common. Class I is a temporary category assigned to three streams that were grossly impaired when the system was established. Classes A-Closed and A-1 are considered high quality, the principal beneficial use of which is public water supply. The A-Closed class may invoke watershed protection and use restrictions to protect drinking water. Classes B and C each have subsections according to whether they support coldwater or warmwater aquatic life. B-1, B-2, C-1, and C-2 support coldwater aquatic life; B-3 and C-3 support warmwater aquatic life. B and C waters have nearly identical use classifications, but B waters specify drinking water as a beneficial use whereas C waters do not. C-3 streams are suitable for warmwater aquatic life and recreation. Because these streams often contain naturally high total dissolved solids (salinity), their quality is marginal for drinking and agricultural and industrial uses.

In August 2003 Montana added four additional classes: D, E, F, and G. The classes include ephemeral streams (E-1, E-2), ditches (D-1, D-2), seasonal or semi-permanent lakes and ponds (E-3, E-4, E-5), and waters with low or sporadic flow (F-1). G-1 waters must be maintained for watering wildlife and livestock and supporting secondary contact recreation and aquatic life, not including fish. These waters are marginally suitable for irrigation after treatment or with mitigation measures and includes “holding water” from coal bed methane development. Note: The classification system designated uses for waterbodies as present at the time of classification in 1955.

Waterbodies may now have other realized uses that are not officially designated. In such cases, a waterbody may be reclassified to officially recognize these other uses. Conversely, designated uses cannot be removed from a waterbody without a formal Use Attainability Analysis and approval under rulemaking by the Montana Board of Environmental Review. Streams forming the boundary of Indian Reservations are coded as State of Montana (SOM) waters for practical reasons related to enforcing Federal and Montana water quality standards. In some cases meanders, canals, and ditches that transect the boundary and then reconnect with a border stream are also coded as SOM waters even when they are located in part or entirely within the Indian Reservation. As a result of this coding protocol,

If you use the "select by location" procedure to identify streams that are completely within one of the reservations, the resulting selected records may include a small number of streams coded as SOM in the "Authority Entity" field. This is not a mistake and needs to be kept in mind when interpreting selection results. Streams that are not parallel to or located on a border but that cross into and are entirely within an Indian Reservation retain the use class as designated by the ARM description for the watershed they are part of but they are designated as "Not State Jurisdiction" or NSJ in the event table's "Jurisdiction" field and the name of the tribe is recorded in the "Authority Entity" field. The name of the reservation is recorded in the "Area Name" field. Streams that are not parallel to or located on a border but that cross into and are entirely within national parks, wilderness areas or primitive areas are assigned a use class of A-1 as specified by ARM Title 17 Chapter 30 Subchapter 614. The name of the park, primitive area, or wilderness area is recorded in the "Area Name" field of the event table. As a consequence, a stream crossing a border will likely have different use classes on either side of the border.

Statutes, Rules, and Regulations

Circular Titles/Descriptions

  • DEQ 1 - Standards for Water Works
  • DEQ 2 - Design Standards for Wastewater Facilities
  • DEQ 3 - Standards for Small Water Systems
  • DEQ 4 - Montana Standards for On-Site Subsurface Sewage Treatment Systems 2013 Edition
  • DEQ 7 - Montana Numeric Water Quality Standards
  • DEQ 8 - Montana Standards for Subdivision Storm Drainage
  • DEQ 10 - Standards for the Development of Springs for Public Water Systems
  • DEQ 11 - Montana Standards for Development of Springs for Individual and Shared Non-Public Systems
  • DEQ 12A - Montana Base Numeric Nutrient Standards
  • DEQ 12B - Nutrient Standards Variances
  • DEQ 13 - Montana Policy for Nutrient Trading
  • DEQ 16 - Standards for Hauled Water Cisterns (Water Storage Tanks) for Non-Community Public Systems
  • DEQ 17 - Montana Standards for Cisterns (Water Storage Tanks) for Individual Non-Public Systems
  • PWS 5 - Groundwater under the Direct Influence of Surface Water
  • PWS 6 - Source Water Protection Delineation
Program/Responsibility DEQ PWS
Coal Bed Methane                        
Discharge Permits                      
Drinking Water Supply            
Facility Design Standards                            
Ground Water Remediation                            
Mixing Zones                          
Water Quality Monitoring                          
Nonpoint Source                        
Source Water Protection                          
TMDL Program                      
Wastewater Systems                          
Water Pollution Control SRF                          
Water/Wastewater Operator Certification                            
National Drinking Water Regulations
Public Water and Sewage Systems
Consumer Confidence Report Rule
Lead and Copper Rule
Disinfectant Byproducts Rule
Montana Chlorination Rule
Surface Water Treatment Rule
Total Coliform Rule
Water Treatment Operators
Drinking Water State Revolving Fund

General Resources

Total Maximum Daily Load Maps & Documents

TMDL Project Map

*TMDLs are specific to a waterbody segment - pollutant combination. Some project areas with completed TMDLs may still require TMDL development for additional waterbody-pollutant combinations. Priority areas are subject to change.

Click here for a more detailed PDF version of this map

Final TMDL Documents

Choose a river basin below to view a list of associated TMDL documents.

Note: Dates next to each TMDL document are the EPA approval dates. Some documents may have had edits made after this date and will include a detailed listing of the changes. Always check DEQ's website for the most recent document version.

Visit the Lakes, Streams and Wetlands Program page to view final TMDL documents listed alphabetically in smaller file sizes with appendices and attachments as separate files


Bitterroot Watershed
Blackfoot River Watershed
Bobtail Creek
Clark Fork River
Flathead River Basin
Flint Creek Watershed
Little Blackfoot
Ninemile Creek
Prospect Creek
Rock Creek
St Regis
Swan Lake
Approved TMDL Documents TMDL Implementation Evaulations
Thompson River Watershed
Tobacco River Watershed

Upper Missouri

Beaverhead River Watershed
Big Hole River Watershed
Boulder-Elkhorn Project Area
Gallatin River Watershed
Jefferson River Watershed
Lake Helena Watershed
Madison River Watershed
Red Rock
Project Website
Sheep Creek
Approved TMDL Documents Project Website

Lower Missouri


Use EPA's Enforcement and Compliance History Online website to search for facilities in your community to assess their compliance with environmental regulations. You can use ECHO to:

  • Search for Facilities
  • Investigate Pollution Sources
  • Search for EPA Criminal and Civil Enforcement Cases
  • Examine and Create Enforcement-Related Maps
  • Analyze Trends in Compliance and Enforcement Data
  • Explore your State's Performance

Please Note: The data online is provided as a public resource and does not always reflect the most up to date information.

Hi, I can help answer your questions!