Protecting Public Health and the Environment.

Idaho Pollutant Discharge Elimination System Program

In 2014, the Idaho Legislature revised Idaho Code to direct DEQ to seek EPA authorization for a state-operated pollutant discharge elimination system permitting program. DEQ submitted a primacy application that adheres to the Clean Water Act and 40 CFR 123 to EPA on August 31, 2016. On June 5, 2018, EPA approved the Idaho Pollutant Discharge Elimination System (IPDES) Program and authorized the transfer of permitting authority to the state beginning on July 1, 2018. The goal of IPDES, like NPDES, is to address water pollution by regulating point sources that discharge pollutants to waters of the United States.

DEQ expects this new state-run program to be a positive development for environmental and regulated entities. Implementing this significant program brings exciting challenges to the agency. The full program will employ 29 positions located in DEQ's state and regional offices and estimates an annual budget of $3 million. Protective, substantive permitting requirements will remain; however, permittees will gain access to permit writers and other staff with local experience and knowledge and to a streamlined process for issuing permits.

The following is the phased transfer schedule for permitting authority:

Date of transfer Sector
July 1, 2018 Publicly owned treatment works and pretreatment program
July 1, 2019 Industrial direct dischargers
July 1, 2020 Facilities covered under general permits, except storm water
July 1, 2021 Storm water (municipal, construction, and industrial), biosolids, and federal facilities

IPDES Permitting

DEQ’s IPDES Program will administer the discharge of pollutants into waters of the United States in Idaho. These discharges include municipal, industrial, storm water, pretreatment controls for certain discharges to publicly owned treatment works (POTWs), and the sewage sludge (biosolids) management program. DEQ is approved to administer the IPDES Program through the Clean Water Act and the “Rules Regulating the Idaho Pollutant Discharge Elimination System Program” (IDAPA 58.01.25).

To issue permits for discharging domestic and nondomestic wastewater and storm water to waters of the United States in Idaho, the IPDES Program will develop applicable permits authorizing effluent discharges and fact sheets describing how permit conditions are developed. IPDES permits will be written to comply with the state water quality standards and limit the amount of pollution that point sources may discharge into surface waters. Learn more.

Guidance Development

A technical guidance committee helps DEQ staff prepare guidance documents related to the implementation of IDAPA 58.01.25. Topics discussed include applying for and composing permits, collecting and submitting information for individual or general discharge permits, and documenting procedures, practices, and requirements for permit writers. Learn more.

Primacy Application

On August 31, 2016, DEQ submitted to EPA for review a program application petitioning for the authority to become the discharge permitting authority in Idaho. Read how DEQ received permitting authority to address water pollution by regulating point sources that discharge pollutants to Idaho’s surface water. Learn more.


DEQ’s pretreatment program regulates pollutants from industrial and commercial facilities that discharge directly into POTWs. Learn more.


Sewage sludge is the solid, semisolid, or liquid untreated residue created during the wastewater treatment process. When treated and processed, sludge becomes biosolids, which are the stabilized residuals that settle from the water during the treatment process. Biosolids may be disposed of or beneficially re-used. Learn more.

IPDES Compliance Monitoring and Enforcement

In the IPDES Program, Compliance, Inspection, and Enforcement (CIE) reviews documents submitted by permittees, inspects facilities, and determines if permittees are complying with their IPDES permits. Additionally, the CIE will provide compliance assistance to facilities.

Inspections of IPDES-permitted facilities occur according to the frequency outlined in DEQ’s Compliance Monitoring Strategy. For most major industrial and municipal facilities, inspections will be conducted every other year, while for most minor industrial and municipal facilities, inspections will occur once in a 5-year period. However, DEQ may choose to inspect more frequently.

The IPDES User’s Guide Volume 1 provides general information for complying with an IPDES permit. Subsequent volumes specific to the discharge sector provide more detailed information about the specific type of permit and expected compliance conditions. Learn more.