Summary of Montana's Water Reuse Guideline or Regulation for Environmental Restoration

This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Treated Municipal Wastewater.

On this page:

• Technical basis
• Water reuse for environmental restoration approved for use in Montana
• Water reuse treatment category for environmental restoration
• Additional context and definitions
• Water reuse for environmental restoration specifications (table)
• Upcoming state law or policy
• References
• Disclaimer

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This page is a summary of the state’s water reuse law or policy and is provided for informational purposes only. Please always refer to the state for the most accurate and updated information. 

In Montana, water reused for environmental restoration environmental restorationThe use of recycled water to create, sustain, or augment water bodies including wetlands, aquatic habitats, or stream flow. Includes groundwater or aquifer recharge for protection from saltwater intrusion , stream flow augmentation and wildlife habitat, and source water protection. include aquifer recharge, aquifer injection and streamflow augmentation. The source of water (treated municipal wastewater) treated municipal wastewater Treated wastewater effluent discharged from a centralized wastewater treatment plant of any size. Other terms referring to this source of water include domestic wastewater, treated wastewater effluent, reclaimed water, and treated sewage. is specified by the state as municipal wastewater. The write-up below uses state terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer's (REUSExplorer's) terms.

Technical basis

Montana approves the use of reclaimed wastewater for reuse applications related to environmental restoration, including for aquifer recharge, aquifer injection and augmentation of stream flow for non-potable purposes. All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.), including its implementing regulations, must be met in addition to any state water quality standards. Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators for environmental restoration-related applications and are summarized in the table. The technical basis for developing the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators is not explicitly specified.

Water reuse for environmental restoration approved for use in Montana

• Aquifer recharge (Class A-1)
• Aquifer injection (Class A-1)
• Stream flow augmentation including fisheries support or recreational enhancement with unrestricted access (Class B)

Water reuse treatment category for environmental restoration

In Montana, the various classes of reclaimed water treatment are defined by their respective treatment requirements and applicable performance standards. 

• For Class A-1 reclaimed wastewater, the treatment requirements are secondary treatment, oxidation, coagulation, filtration and disinfection to achieve a BOD and TSS of ≤10 mg/L and a turbidity of ≤2 NTU (average), ≤5 NTU (single sample maximum) and total coliform organisms ≤2.2 CFU/100 mL (7-day median) and ≤23 CFU/100 mL (single sample maximum). Class A-1 reclaimed wastewater has an additional total nitrogen requirement of ≤5 mg/L (Circular DEQ 2).
• For Class B reclaimed wastewater, the treatment requirements are secondary treatment, oxidation, settling and disinfection to achieve total coliform organisms ≤2.2 CFU/100 mL (7-day median) and ≤23 CFU/100 mL (single sample maximum). 

Additional context and definitions

In Montana, reclaimed wastewater is defined as “wastewater treated by a public sewage system for reuse for private, public, or commercial purposes” (Circular DEQ 2).

Aquifer injection and aquifer recharge are considered separate from indirect potable reuse in Montana. Indirect potable reuse, the intentional return of reclaimed wastewater to augment raw water supplies, is discussed in Montana’s potable reuse summary. Montana defines aquifer injection as the use of a well to inject water directly into an aquifer system without filtration through the geologic materials overlying the aquifer system for the purpose of aquifer recharge or for an aquifer storage and recovery project (Circular DEQ 2). Aquifer recharge is the controlled subsurface addition of water directly to the aquifer or the controlled application of water to the ground surface for the purpose of replenishing the aquifer to offset adverse effects resulting from the net depletion of surface water (Circular DEQ 2). An aquifer storage and recovery project involves the use of an aquifer to temporarily store water through various means, including injection, surface spreading and infiltration, drain fields or another method approved by the Department of Natural Resources and Conservation (Circular DEQ 2). The stored water may be either pumped from the injection well or other wells for beneficial use or allowed to naturally drain away. Montana indicates that even though Class A-1 and Class B-1 reclaimed wastewater may meet most drinking water standards, direct reuse for human consumption is not permitted.

Per Mont. Admin. R. 75-5-410, reclaimed wastewater proposed for aquifer infiltration or aquifer recharge must, at a minimum, meet level two treatment for the removal of nitrogen. The effluent quality must meet either primary drinking water standards or non-degradation requirements prior to discharge (Circular DEQ 2). Soil aquifer treatment may not be considered in meeting these provisions for augmentation. Any discharge to surface water must be authorized under an NPDES or MPDES permit and meet the provisions of the permits.

Montana requires that conveyance systems for the delivery of municipal reclaimed wastewater must be easily identifiable; the use of purple piping or purple striped piping is encouraged (Circular DEQ 2). Reclaimed water plumbing must not be cross-connected to any potable water supply within the structure. Areas of reclaimed wastewater use must have signs posted at conspicuous public access points that read “Reclaimed wastewater – Do Not Drink” or an approved equivalent warning.

Water reuse for environmental restoration specifications

Summary of Montana's Water Reuse for Environmental Restoration Specifications

Source= Circular DEQ 2

* Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the State-specific regulations.

Upcoming state law or policy

No upcoming environmental restoration reuse regulations were found for Montana.

References

Clean Water Act, 33 U.S.C. §§ 1251 et seq.

Design Standards for Public Sewage Systems, Circular DEQ 2.

Water quality requirements -- aquifer recharge or certain mitigation plans -- minimum requirements. Mont. Admin. R. 75-5-410.
 

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Disclaimers

Please contact us at [email protected] if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.