Page Contents
What is a TMDL?
A total maximum daily load (TMDL) is the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. A TMDL can often be calculated using a simple equation that involves streamflow and pollutant concentration to express the allowable load in pounds per day, although the TMDL can also be expressed as a percent reduction in loading.
TMDLs being Written for the Tongue River
At this time, Montana DEQ is not writing any TMDLs for the Tongue River. This page will be updated if there are future changes and TMDL development is initiated.
Why DEQ Writes TMDLs
TMDLs address cumulative water quality impacts within a watershed and incorporate multiple types of pollution sources – both regulated and unregulated. Pollution to our waterbodies is not always caused by permitted surface water discharges (such as from a mine, wastewater treatment facility, or construction site) and water quality problems may not always be solved by adjusting permit limits. Sources of pollution may instead be from unregulated land management activities and/or natural sources, or from a combination of all three types of sources. In all of these cases, a TMDL can be an avenue for developing water quality improvement solutions.
Waterbodies impaired by a pollutant are not fully supporting all of their beneficial uses designated by the state of Montana (such as drinking water, agricultural uses, and support of aquatic life). Under Montana state law and the federal Clean Water Act, TMDLs must be written for waterbodies that do not meet water quality standards due to impairment by a pollutant. The water quality standards for EC and SAR for the Tongue River can be viewed on the Tongue River Water Quality Standards page.
Tongue River Salinity Project Contacts
See the Tongue River Watershed Project Contacts page for a full description of each project team member’s role and for a list of additional contacts.
Click on the Adobe Reader icon if you need to download the free Adobe Acrobat software to view the PDF documents on this page.
Page Released: July 6, 2016
Last Updated: May 24, 2023
