Summary of Montana's Water Reuse Guideline or Regulation for Agriculture
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 agriculture approved for use in Montana
- Water reuse treatment category for agriculture
- Additional context and definitions
- Water reuse for agriculture 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 reuse for water reuse for agricultureThe use of recycled water for production of both crops for human consumption and non-food crops of commercial value. This reuse application excludes consumption by livestock, onsite non-potable reuse, and landscaping. includes drip or subsurface irrigation of root crops, food crops where there is no reclaimed wastewater contact with the edible portion of the crop and trees and spray irrigation of trees and fodder, fiber and seed crops; sod, ornamental plants for commercial use and pasture to which milking cows or goats have access; and food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents. 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 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 water for agriculture, including spray irrigation of nonfood crops, drip or subsurface irrigation of nonfood crops, spray irrigation of food crops (e.g., any crops intended for human consumption) and drip or subsurface irrigation of food crops (Circular DEQ 2). Montana requires that reclaimed wastewater reuse projects have documentation from the Department of Natural Resources and Conservation that the change of appropriation or water right was approved, or that no authorization is needed under Title 85, Water Use (Circular DEQ 2). 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 relevant rule requirements under the Food Safety Modernization Act (FSMA) (124 Stat. 3885). Treatment requirements and performance standards are applied for the removal of pathogen and chemical contaminants for reuse applications related to agricultural irrigation to ensure “an adequate demonstration of public health and environmental protection” (Circular DEQ 2). 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 agriculture approved for use in Montana
Circular DEQ 2 defines the following approved water reuse for agriculture:
- Drip or subsurface irrigation of
- Root crops
- Greater than agronomic uptake rate (Class A-1)
- At or below the agronomic uptake rate (Class A)
- Food crops where there is no reclaimed wastewater contact with edible portion of crop (e.g., orchards, vineyards)
- Greater than agronomic uptake rate (Class B-1)
- At or below the agronomic uptake rate (Class B)
- Trees
- Greater than agronomic uptake rate (Class B-1)
- At or below the agronomic uptake rate (Class D)
- Root crops
- Spray irrigation of
- Trees and fodder, fiber and seed crops
- Greater than agronomic uptake rate (Class B-1)
- At or below the agronomic uptake rate (Class D)
- Sod, ornamental plants for commercial use and pasture to which milking cows or goats have access
- Greater than agronomic uptake rate (Class B-1)
- At or below the agronomic uptake rate (Class C)
- Food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents
- Greater than agronomic uptake rate (Class B-1)
- At or below the agronomic uptake rate (Class C)
- Trees and fodder, fiber and seed crops
Water reuse treatment category for agriculture
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards, differentiated by the degree of additional treatment provided following secondary treatment (Circular DEQ 2). The respective treatment requirements are briefly summarized regarding water reuse for agriculture:
- 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 A reclaimed water, 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) and ≤5 NTU (single sample maximum).
- 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.
- 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).
- For Class C reclaimed wastewater, the treatment requirements are oxidation, settling and disinfection to achieve ≤23 CFU/100 mL (7-day median) and ≤240 CFU/100 mL (single sample maximum).
- For Class D reclaimed wastewater, the treatment requirements are oxidation and settling. Disinfection is generally not be required for Class D reclaimed wastewater; however, proximity to areas of public access or habitation may dictate that disinfection be provided in order to protect public health.
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). The “agronomic rate” refers to the controlled application of treated effluent (reclaimed wastewater) from public sewage treatment facilities to crops in a manner such that all nutrients are utilized by the crop and no impact to groundwater or surface water occurs (Circular DEQ 2).
Montana does not have public access buffer zones for Class A water but requires buffer zones of 50 feet for Class B and C reclaimed wastewater and 200 feet for Class D reclaimed wastewater (Circular DEQ 2). No dwelling, residential property or areas with public access are allowed within the buffer zone.
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 agriculture specifications
Summary of Montana's Water Reuse for Agriculture Specifications
| Recycled Water Class/Category | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Class A-1; greater than agronomic uptake rate (Spray irrigation of fodder, fiber, seed crops, sod, ornamental plants for commercial use, pasture to which milking cows and goats have access and food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents; Spray, drip, or subsurface irrigation of trees; Drip or subsurface irrigation of root crops and food crops where there is no reclaimed wastewater contact with the edible portion of the crop) |
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 A; at or below the agronomic uptake rate (Spray irrigation of fodder, fiber, seed crops, sod, ornamental plants for commercial use, pasture to which milking cows and goats have access and food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents; Spray, drip, or subsurface irrigation of trees; Drip or subsurface irrigation of root crops and food crops where there is no reclaimed wastewater contact with the edible portion of the crop) |
Municipal wastewater |
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 |
Measured following treatment |
||
|
Turbidity |
≤2 NTU (average) ≤5 NTU (single sample maximum) |
Continuous monitoring |
||
|
Total nitrogen |
Not specified |
A minimum of monthly analysis during periods of use (including prior to seasonal startup) |
||
|
Phosphorusa |
Not specified |
Not specified |
||
|
Class B-1; greater than agronomic uptake rate (Spray irrigation of fodder, fiber, seed crops, sod, ornamental plants for commercial use, pasture to which milking cows and goats have access and food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents; Spray, drip, or subsurface irrigation of trees; Drip or subsurface irrigation of food crops where there is no reclaimed wastewater contact with the edible portion of the crop) |
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 |
||
|
Phosphorusa |
Not specified |
Not specified |
||
|
Class B; at or below the agronomic uptake rate (Spray irrigation of fodder, fiber, seed crops, sod, ornamental plants for commercial use, pasture to which milking cows and goats have access and food crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents; Spray, drip, or subsurface irrigation of trees; Drip or subsurface irrigation of food crops where there is no reclaimed wastewater contact with the edible portion of the crop) |
Municipal wastewater |
Total coliform |
≤2.2 CFU/100 mL (7-day median) ≤23 CFU/100 mL (single sample maximum) |
Weekly analysis |
|
Total nitrogen |
Not specified |
A minimum of monthly analysis during periods of use (including prior to seasonal startup) |
||
|
Phosphorusa |
Not specified |
Not specified |
||
|
Class C; at or below the agronomic uptake rate (Spray irrigation of sod, ornamental plants for commercial use and pasture to which milking cows or goats have access, crops which undergo physical or chemical processing sufficient to destroy all pathogenic agents) |
Municipal wastewater |
Total coliform |
≤23 CFU/100 mL (7-day median) ≤240 CFU/100 mL (single sample maximum) |
A minimum of monthly analysis during periods of use (including prior to seasonal startup) |
|
Total nitrogen |
Not specified |
A minimum of monthly analysis during periods of use (including prior to seasonal startup) |
||
|
Disinfectant residual |
Not specified |
Weekly if chemical disinfection is being utilized |
||
|
Class D; at or below the agronomic uptake rate (Drip or subsurface irrigation of trees; Spray irrigation of trees and fodder, fiber and seed crops |
Municipal wastewater |
Total nitrogen |
Not specified |
A minimum of monthly analysis during periods of use (including prior to seasonal startup) |
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 regulations pertaining to water reuse for agriculture were found for Montana.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Food Safety Modernization Act (FSMA), 124 Stat. 3885.
Design Standards for Public Sewage Systems, Circular DEQ 2.
Please contact us at waterreuse@epa.gov 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.