Key Takeaways

• What Is Happening? The Washington State Department of Ecology (Ecology) published its final 2025 Industrial Stormwater General Permit (ISGP), which authorizes the discharge of stormwater and certain conditionally authorized “non-stormwater” discharges from industrial activities in the State of Washington. The final 2025 ISGP took effect and superseded the 2020 ISGP on January 1, 2025.
• Who Is Impacted? Industrial facilities in Washington.
• What Should I Do? For industrial facilities that reapplied for ISGP coverage under the new permit or may become subject to the ISGP in the near future, prompt attention to permit requirement changes is prudent to ensure that all permit requirements are understood. Additionally, facilities looking to obtain a conditional no exposure exemption (CNE) in lieu of permit coverage should take note of the significant process change.

As previously reported, Ecology published the proposed 2025 ISGP for public comment last May. The 2025 ISGP contains a number of significant changes from the 2020 ISGP. Notably, it sets forth new Per and Polyfluorinated Substances (PFAS) and 6PPD-quinone (6PPDQ) monitoring requirements for numerous covered facilities, and significantly modifies the process for obtaining CNEs, among other changes. The final 2025 ISGP also differs from the proposed ISGP in several respects. For one, the final 2025 ISGP includes more expansive 6PPDQ reporting requirements than originally proposed. Additionally, the final permit walks back the draft 2025 ISGP’s significantly modified definition of “industrial activity” and questionable purported attempt to require ISGP permit coverage in the first instance for a broader category of transportation facilities than are required by federal law to obtain stormwater discharge permits. A closer examination of these deviations and final changes follows.

Significant Changes from the 2020 ISGP

The 2025 ISGP deviates from the 2020 ISGP in a number of respects, including the following:

• Sampling requirements for 6PPDQ. The 2025 ISGP prescribes a quarterly 6PPDQ sampling requirement for Railroad Transportation (482xxx, 488210), Transit and Ground Passenger Transportation (485xxx, 488490, 487110), Truck Transportation (484xxx), Postal Service (491xxx), Water Transportation (483xxx, 487210, 4883xx, 532411), Air Transportation (481xxx, 487990), Petroleum Bulk Stations and Terminals (4247xx), Warehousing and Storage Facilities (493xxx, 531130), Hazardous Waste Treatment, Storage and Disposal Facilities and Dangerous Waste Recyclers subject to the provisions of Resource Conservation and Recovery Act (RCRA) Subtitle C. The sampling requirement is “report only.” Beginning January 1, 2028, facilities must perform quarterly 6PPDQ sampling and report the results to Ecology. Small businesses are required to monitor 6PPDQ yearly instead of quarterly. The 2025 ISGP adds 6PPDQ to the list of required monitoring parameters for discharges to 303(d) listed waters.

Notably, the final 6PPDQ sampling requirements are significantly more expansive than originally proposed. The 2025 ISGP added two new industries to the 6PPDQ sampling requirement: Hazardous Waste Treatment, Storage and Disposal Facilities, and Dangerous Waste Recyclers subject to the provisions of RCRA Subtitle C. These facilities were not included in the draft permit’s list of facilities subject to the new 6PPDQ sampling requirements. The final 2025 ISGP also replaced the originally proposed blanket monitoring exemption for small businesses with a 1-year (instead of quarterly) monitoring frequency for small businesses. The final 2025 ISGP also added 6PPDQ to the list of required monitoring parameters for discharges to 303(d) listed waters, even though the draft 2025 ISGP was silent on the matter.

• Sampling requirements for PFAS. The 2025 ISGP includes new PFAS sampling requirements for facilities in the waste management sector and for air transportation facilities with known, current, or historical use of Aqueous Film Forming Foam (AFFF). Ecology has determined that these two sectors have the potential for PFAS exposure and stormwater contamination. The sampling requirement is “report only” and begins in 2025. Furthermore, the 2025 ISGP adds that facilities subject to PFAS sampling requirements should also sample their discharges to ground.
• CNE Exemption. The 2025 ISGP eliminates automatic CNE approvals. CNEs are an approved option out of full permit requirements, as well as the costs and exposure resulting from ISGP coverage. Under the new permit, CNE will only be granted if Ecology informs the applicant in writing that the application is approved. This change stands to have significant implications. Historically, in Washington, unless Ecology expressly denied a proper and complete CNE application within 90 days, it was deemed automatically approved. Many, if not all, CNEs currently in effect in Washington were approved in this way. Ecology did commit in the final 2025 ISGP to respond to all CNE requests in writing within 90 days (unlike the open-ended review period originally proposed in the draft 2025 ISGP). Nonetheless, given historical practices and current Ecology backlogs, there is a real possibility Ecology will not be able to process and respond to all CNE applications within 90 days. As a result, facilities that qualify for a CNE may be required to obtain full ISGP coverage and comply with onerous permit requirements while waiting for Ecology to approve their proper CNE requests.
• Annual Gross Revenue Reporting Deadline. The final 2025 ISGP expressly includes an Annual Gross Revenue Reporting obligation and a deadline of May 15, whereas the 2020 ISGP was silent on the matter.
• New Level 3 Engineering Report Deadline. The final 2025 ISGP sets forth a new Level 3 Engineering Report Deadline of “[n]o later than 6 months after the last day of the calendar year in which the Level 3 was triggered, i.e., due June 30”, whereas the Draft 2025 ISGP and prior ISGPs set forth a deadline of May 15 prior to the Level 3 deadline.
• Functional equivalent groundwater sampling. In addition to now requiring facilities subject to PFAS stormwater monitoring to also sample any on-site discharges to ground (e.g., infiltration), the final 2025 ISGP also provides that a facility must also sample on site discharges to ground if Ecology deems a discharge point to groundwater a functional equivalent to a point source discharge to surface waters.
• Slightly modified definition of “Industrial Activity”. The 2025 ISGP retains the 2020 ISGP definition of industrial activity but adds additional text expressly stating that, for purposes of the permit requirements, “industrial activity”(1) “excludes areas located on plant lands separate from the plant's industrial activities, such as office buildings and accompanying parking lots as long as the drainage from the excluded areas is not mixed with stormwater drained from” industrial activity areas, and (2) it “includes areas at intermodal transportation facilities where material handling occurs”.

This is a significant departure from the entirely rewritten definition of “industrial activity” Ecology originally proposed in the draft 2025 ISGP. In its response to comments, Ecology explained that “[t]he change proposed in the draft permit to the definition of “Industrial Activity” is no longer warranted” due to the Washington Court of Appeals’ interim decision in Puget Soundkeeper All. v. Pollution Control Hearings Bd., 30 Wn. App. 2d 360 (2024), review denied sub nom. Puget Soundkeeper All. v. Pollution Control Hearings, 554 P.3d 1222 (Wash. 2024) (finding that the various requirements of the 2020 ISGP applied to the entire footprint of a transportation facility and not just those areas of the transportation facility that triggered the need for a stormwater permit in the first place). For a more in-depth discussion of the issues at play in the Puget Soundkeeper and parallel federal litigation, see our previous alert and commentaries.

Notably, Ecology also abandoned its initial and questionable attempt in the draft 2025 ISGP to purport to require more transportation facilities to obtain coverage under the ISGP in the first place than are required to obtain an NPDES permit by the federal Clean Water Act’s implementing stormwater regulations.

Implementation

The permit became effective on January 1, 2025, and expires December 31, 2029. Facilities previously covered under the 2020 ISGP had to reapply for coverage by July 5, 2024. Covered facilities must update their Stormwater Pollution Prevention Plans (SWPPP) to conform to the new permit by May 15, 2025, and all conforming SWPPP updates must be implemented by July 1, 2025.