Summary of Idaho'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 Idaho
- 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
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 Idaho, water reused for 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 groundwater recharge and subsurface distribution, each with their own specific limitations. 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
Idaho approves the use of recycled water for reuse applications related to environmental restoration, including groundwater recharge for non-potable groundwater and subsurface distribution. 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 of the turbidity and total coliform values is California’s Title 22 Water Recycling Criteria (Cal. Code Regs. tit. 22).
Water reuse for environmental restoration approved for use in Idaho
Idaho Admin. Code r.58.01.17 defines the following approved water reuse for environmental restoration:
- Groundwater recharge through surface spreading, infiltration basins or seepage ponds (Class A)
- Note that seepage ponds will be removed from this definition in Idaho’s recycled water rules in July 2023 (Idaho DEQ, 2022).
- Subsurface distribution of recycled water via a distribution system with a point of discharge beneath the earth’s surface, where pollutants cannot be reasonably expected to enter waters of the state in concentrations resulting in injury to beneficial uses (Class D).
- Note that this application will be deleted from Idaho’s recycled water rules in July 2023 (Idaho DEQ, 2022).
Water reuse treatment category for environmental restoration
In Idaho, the various classes of treatment are defined by their respective treatment requirements and applicable performance standards.
- For Class A recycled water, municipal wastewater is required to be “oxidized, coagulated, clarified, and filtered, or treated by an equivalent process and adequately disinfected” (Idaho Admin. Code r. 58.01.17.601). Class A recycled water must be disinfected by either:
- A chlorine disinfection process that meets the requirements for Class A water in the table; or
- A disinfection process that, when combined with filtration, has been demonstrated to achieve 5-log inactivation of virus. “Acceptance by the State of California as published in their Treatment Technology Report for Recycled Water is one method to constitute such a demonstration. (7-1-21)” (Idaho Admin. Code r. 58.01.17.601). Disinfection methods are considered on a case-by-case basis.
- For Class D recycled water, municipal wastewater is required to be oxidized and adequately disinfected to meet the total coliform requirements for Class D recycled water in the table (Idaho Admin. Code r. 58.01.17.601).
Additional context and definitions
Idaho defines recycled water as “water that has been treated by a wastewater treatment system and is used in accordance with the rules” in Idaho Admin. Code r. 58.01.17.
For the non-potable groundwater recharge use, groundwater recharge systems must comply with Idaho Admin. Code r. 58.01.11, “Ground Water Quality Rule.” The minimum requirements for site location and aquifer storage time are be based on site-specific modeling and any source water assessment zone studies for public drinking water wells in the area. The owners of these systems must control the ownership of this down gradient area to prohibit future wells from being drilled in the impact zone of the groundwater recharge system.
The subsurface distribution and use of recycled water must be designed and located so that compliance with Idaho Admin. Code r. 58.01.11, “Ground Water Quality Rule,” is maintained. The discharge to a subsurface distribution system may not exceed the hydraulic, organic, nitrogen or other limitations specified in a permit. Idaho considers past operating performance, the ability of the soils to treat the pollutants in the discharge, hydrogeologic characteristics of the site such as permeability and infiltration rates and other relevant information.
Water reuse for environmental restoration specifications
Summary of Idaho's Water Reuse for Environmental Restoration 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 (Ground water recharge through surface spreading or seepage ponds) |
Municipal wastewater |
Total coliform |
≤2.2 organisms/100 mL (7-day median) ≤23 organisms/100 mL (single sample maximum) |
Daily, or as determined |
|
Turbidity (granular or cloth media filtration) |
≤2 NTU (24-hour mean) ≤5 NTU (single sample maximum) |
Continuous monitoring |
||
|
Turbidity (membrane filtration) |
≤0.2 NTU (24-hour mean) ≤0.5 NTU (single sample maximum) |
|||
|
Total nitrogena |
≤10 mg/L |
Not specified |
||
|
5-day biochemical oxygen demand (BOD5) |
≤5 mg/L (monthly mean) |
Weekly composite samples |
||
|
pH |
6.0–9.0 |
Daily grab samples or continuous monitoring |
||
|
Disinfection requirements contact time |
450 mg-min/L with 90 min of modal time, or Disinfection to 5-log inactivation of virus |
Disinfection requirement |
||
|
Class D (Subsurface distribution of recycled water via a distribution system with a point of discharge beneath the earth’s surface)b |
Municipal wastewater |
Total coliform |
≤230 organisms/100 mL (3-day median) ≤2,300 organisms/100 mL (single sample maximum) |
Once monthly or as determined |
Source= Idaho Admin. Code r. 58.01.17
* 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 This limit may not be applicable if the results of a Department-approved groundwater quality impact assessment indicate that lower limits are necessary to protect the existing ground water quality.
b For Class D recycled water, a maximum total nitrogen limit may be required based on an analysis of ground water quality impacts.
Upcoming state law or policy
Idaho is currently proposing revisions, including the addition of a new General Reuse Permits section, to their Recycled Water Rules in Docket No. 58-0117-2201 (Idaho DEQ, 2022). After consideration of public comments, Idaho DEQ intends to present the final rule proposal to the Idaho Board of Environmental Quality in November 2022. The rule is expected to be final and effective upon the conclusion of the 2023 legislative session if adopted by the board and approved by the Idaho Legislature.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Ground Water Quality Rules, Idaho Admin. Code r.58.01.11.
Idaho Department of Environmental Quality (DEQ). 2022. Recycled Water: Docket No. 58-0117-2201.
Recycled Water Rules, Idaho Admin. Code r.58.01.17.
Water Recycling Criteria, Cal. Code Regs. tit. 22.
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.