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Montana Pollutant Discharge Elimination System (MPDES)

MPDES General Permits

MPDES Individual Permits

Individual Permits Listing

Storm Water Permits

The goal of the Montana Pollutant Discharge Elimination system (MPDES) program is to control point source discharges of wastewater such that water quality in state surface water is protected. Levels of water quality that are required to maintain the various beneficial uses of state surface waters are set forth in the Water Quality Standards (WQS).

All point sources of wastewater discharge are required to obtain and comply with MPDES permits. The effluent limitations and other conditions for certain categories of wastewaters are required to be treated to federally-specified minimum levels based on available and achievable water treatment technologies. Additonally, effluent limits and permit conditions are established to protect beneficial uses and applicable WQS.

The Nondegradation Rules are a part of the WQS that apply to new or increased sources of pollution. These rules prohibit significant increases in discharge of toxic and deleterious materials to state waters, unless it is affirmatively demonstrated to the DEQ that a change is justifiable as a result of necessary economic or social development and will not preclude present and anticipated use of these waters.

Each MPDES permit issued is designed to protect the state surface water quality at the point of discharge. In addition, recognizing the dynamic nature of streams and the potential additive or cumulative effects of pollutants, MPDES permits also address stream reach or basin-wide pollution problems. A calculation process called total maximum daily load (TMDL) is used to apportion allowable pollutant discharge levels among the various dischargers. If reductions of a given pollutant in a stream reach or basin are found necessary to meet WQS, the TMDL process is used to apportion the reductions among the dischargers in that reach or basin.

The program is funded by application and annual permit fees. Activities of program staff include public education, reviewing applications, determining effluent limits and best management practices, environmental assessments, public participation and information retrieval, effluent and instream data review and management, field inspections, enforcement, regulation and guidance preparation, program planning and administration.


MPDES General Permits

An MPDES General Permit is a pre-existing permit for wastewater discharges associated with common activities, such as concentrated animal feeding operations and storm water discharges from construction or industrial activity. Authorizations for General Permits are issued if a facility or activity falls within the guidelines of the existing permit. The process for obtaining authorization under a General Permit is expedient and consists of application, review, and authorization within 30 days.

General Permits

Storm Water Permits

Permits for storm water run off associated with Construction, Industrial, Mining & Oil & Gas Extraction Activities and Small Municipal Separate Storm Sewer Systems.


MPDES Individual Permits

Individual MPDES Permits regulate wastewater discharges from point sources that do not fall under the guidelines for a General Permit. The individual permitting process is more rigorous, as individual permits address the specific conditions of the facility or activity needing authorization.

Current permits are available in PDF format on the Individual Permits Listing page.

Individual Permit Application Forms

  1. New industrial or commercial dischargers
    Form 1 General Information
    EPA Application Form 2D
  2. Existing industrial or commercial dischargers
    Form 1 General Information, Consolidated Permits Program,
    EPA Form 3510-1. Application Form 2C
  3. Municipal dischargers
    (Domestic Sewage Treatment Lagoons)
    EPA Application Form 2A