Summary of Montana's Water Reuse Guideline or Regulation for Impoundments
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 impoundments approved for use in Montana
- Water reuse treatment category for impoundments
- Additional context and definitions
- Water reuse for impoundments specifications (table)
- Upcoming state law or policy
- References
- Disclaimer
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 impoundmentsThe use of recycled water in an impoundment (body of water within an enclosure). This includes both unrestricted (use of reclaimed water in an impoundment in which no limitations are imposed on body-contact water recreation activities) and restricted (use of reclaimed water in an impoundment where body contact is restricted). Includes recreational impoundments, aesthetic impoundments, and ornamental impoundments with and without public access. Excludes landscape impoundments and storage of recycled water intended for other specific reuse applications (e.g., for agricultural irrigation). include restricted and unrestricted recreational impoundments. The source of water 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 municipal wastewater for recreational impoundments with both restricted and unrestricted access and body and non-body contact recreation. 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. Impoundments that are permitted for unrestricted recreation have more stringent performance standards than impoundments with restricted recreation. Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators related to impoundments 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 impoundments approved for use in Montana
Circular DEQ 2 defines the following approved water reuse for impoundments:
- Unrestricted recreational impoundments (Class A-1)
- Restricted recreational impoundments (Class A-1 and Class B-1)
Water reuse treatment category for impoundment-related reuse applications
The various classes of reclaimed wastewater are defined by their respective treatment requirements and applicable performance standards, differentiated by the degree of additional treatment provided following secondary treatment.
- 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.
- For Class B-1 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). Class B-1 reclaimed wastewater has an additional total nitrogen requirement of ≤5 mg/L.
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). An impoundment is defined as “a basin, naturally formed or artificially built, which is dammed or excavated for the retention of water, slurry, sediment, waste or other liquid or semi-liquid material” (Mont. Code Ann. § 17-24-301).
In Montana, “restricted recreational impoundments” fishing ponds. Restricted recreational impoundments are defined as a body of reclaimed wastewater where recreation is limited to fishing, boating and other non-body-contact water recreation activities, or a body of reclaimed wastewater used for aesthetic features or otherwise serves a function not intended to include public contact (Circular DEQ 2). “Unrestricted recreational impoundment” is defined as a body of reclaimed wastewater on which no limitations are imposed on body contact water recreation activities (Circular DEQ 2).
For recreational impoundments, Montana requires a pond management plan to ensure control of algae, weeds and erosion due to wind or other impacts; a plan for maintenance of water balance to ensure overflow will not occur; and the use of best management practices such as signage, control structures and liners where appropriate (Circular DEQ 2).
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 (Circular DEQ 1). 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 impoundments specifications
Summary of Montana's Water Reuse for Impoundments Specifications
| Recycled Water Class/Category (Approved Uses) | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Class A-1 (Unrestricted recreational impoundments and restricted recreational impoundments) |
Municipal wastewater |
Total nitrogen |
≤5 mg/L |
Biweekly analysis |
|
Total coliform |
≤2.2 CFU/100 mL (7-day median) ≤23 CFU/100 mL (single sample maximum) |
Weekly analysis |
||
|
5-day biochemical oxygen demand (BOD5) |
≤10 mg/L |
Measured following treatment |
||
|
Total suspended solids (TSS) |
≤10 mg/L |
|||
|
Turbidity |
≤2 NTU (average) ≤5 NTU (single sample maximum) |
Continuous monitoring |
||
|
Phosphorusa |
Not specified |
Not specified |
||
|
Class B-1 (Restricted recreational impoundments) |
Municipal wastewater |
Total nitrogen |
≤5 mg/L |
Biweekly analysis |
|
Total coliform |
≤2.2 CFU/100 mL (7-day median) ≤23 CFU/100 mL (single sample maximum) |
Weekly analysis |
||
|
Phosphorus |
Not specified |
Not specified |
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.
a Phosphorus monitoring might be required if there are changes in concentration of total inorganic phosphorus in ground water, if water quality protection practices approved by the department have been fully implemented and if an evaluation of the phosphorus adsorptive capacity of the soils in the area of the activity indicates that phosphorus will be removed for a period of 50 years prior to a discharge to any surface waters. Contact the state for more information on this.
Upcoming state law or policy
No upcoming reuse regulations related to impoundments were found for Montana.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Design Standards for Public Sewage Systems, Circular DEQ 2.
Cross-Connections in Drinking Water Supplies, Mont. Code Ann. § 17-38-3.
Standard for Water Works, Circular DEQ 1.
Strip and Underground Mine Reclamation Act: Definitions and Strip Mine Permit Application Requirements, Definitions, Mont. Code Ann. § 17-24-301.
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.