DEQ finalizes new industrial stormwater permit

BOISE — The Idaho Department of Environmental Quality on Thursday announced the finalization of the Idaho Pollutant Discharge Elimination System Multi‑Sector General Permit, a regulatory tool governing stormwater discharges from industrial facilities statewide. The permit takes effect May 2, 2026. 

The announcement is critical for companies operating in Idaho that discharge industrial stormwater. Such discharges are regulated under the federal Clean Water Act, and companies engaging in these activities must have a permit in place to operate legally. Failure to comply with the new permit could result in enforcement actions or require operators to obtain individual permits. 

According to DEQ, the permit followed a state‑required public participation process that included the release of a draft permit in December 2025 and a public comment period that closed in early February. DEQ said it reviewed all submitted comments and included its responses in the permit decision fact sheet. 

The Multi‑Sector General Permit applies to industrial facilities that discharge stormwater to surface waters, including manufacturing operations, mining sites, wood products facilities, recycling centers, transportation yards and certain warehouses with outdoor industrial activities. Facilities covered by the permit must implement pollution prevention measures, conduct inspections and monitoring, and meet reporting requirements designed to reduce pollutants such as sediment, metals, oils and chemicals from entering Idaho’s waterways. 

Under state rules, entities covered by a general IPDES permit may not challenge permit conditions through DEQ’s administrative process. Instead, companies may either challenge the permit in court or apply for an individual IPDES permit if the general permit does not suit their operations. 

Facilities operating under the previous permit, as well as those seeking new coverage, should review the final permit to ensure compliance by the May 2 effective date. The final permit and fact sheet are available at www.deq.idaho.gov.