The Washington 2025 Industrial Stormwater General Permit (ISGP) took effect on January 1, 2025, and was originally scheduled to run through December 31, 2029.
However, the state's Department of Ecology (Ecology) has issued a modified permit that shortens the permit term by one year. The modification takes effect November 20, 2026, and moves the expiration date to December 31, 2028; all other permit provisions remain unchanged.
What it means for those operating in Washington
Your current obligations stay the same, but your renewal timeline is about a year shorter than planned. All permits must be resubmitted no later than July 3, 2029.
Covered facilities remain responsible for stormwater pollution prevention, monitoring, reporting, and appropriate control measures under the permit currently in effect. These requirements help manage runoff from manufacturing sites, equipment yards, transportation facilities, and other industrial properties that can carry pollutants into nearby waterways and increase environmental and compliance risks.
With the renewal schedule accelerated, facility managers and environmental, health and safety (EHS) leaders should assess whether their stormwater programs reflect current site conditions, permit obligations, and day-to-day operations.
Seven stormwater compliance gaps to fix before your next inspection
1. Your SWPPP no longer reflects site conditions
A Stormwater Pollution Prevention Plan (SWPPP) should reflect the facility's current operations, potential pollutant sources, and pollution prevention controls.
But sites change. New equipment, outdoor storage, production changes, construction, material handling, and drainage modifications can introduce risks that an older SWPPP may not adequately address.
What to check: Does your SWPPP accurately reflect current operations, outdoor activities, drainage pathways, pollutant sources, and control measures? Have changes at the facility triggered a need to review or update the plan?
2. Outdoor materials and activities create overlooked exposure
Rainfall can contact materials, equipment, waste, vehicle fluids, and other potential pollutant sources before flowing into a drainage system.
Even well-managed facilities can overlook exposure points in outdoor storage areas, loading docks, equipment maintenance zones, and waste-handling locations.
What to check: Walk the site during normal operations. Look for uncovered materials, leaking equipment, spills, inadequate containment, and activities that could expose pollutants to rainfall or runoff.
3. Monitoring results aren't driving corrective action
Collecting samples and doing visual inspections are only one part of an effective stormwater program. Results need to be evaluated against applicable permit requirements, and potential problems need to be investigated and addressed.
Recurring exceedances, inconsistent sampling practices, or poorly documented follow-up can indicate that the underlying source of a problem remains unresolved.
What to check: Review recent monitoring results, applicable benchmarks and discharge limits, reporting records, corrective actions, and documentation. Determine whether recurring issues have been investigated and whether corrective measures are working.
4. Employees and contractors aren't following established controls
Stormwater controls can fail when employees and contractors don't understand their responsibilities or when procedures aren't practical for daily operations. Material handling, vehicle and equipment maintenance, spill response, and housekeeping can all affect stormwater quality.
What to check: Confirm that personnel understand relevant procedures, spill-response expectations, material storage requirements, and the controls that apply to their work areas. Check whether training and inspections are documented as required.
5. Inspection and maintenance records leave unanswered questions
A control measure may appear adequate on paper but fail in practice if it is damaged, clogged, poorly maintained, or inspected inconsistently.
Incomplete records can also make it difficult to demonstrate that required activities occurred and identified problems were addressed.
What to check: Review inspection schedules, completed inspection forms, maintenance records, deficiencies, corrective-action documentation, and required reports. Verify that responsibilities and deadlines are clearly assigned.
6. Emerging contaminants haven't been considered where applicable
Stormwater compliance can involve more than conventional sediment and visible pollutants. Washington's industrial stormwater requirements include pollutant-specific sampling provisions for certain facilities, including requirements involving per- and polyfluoroalkyl substances (PFAS) and 6PPD-quinone.
Applicability depends on the facility, permit conditions, and relevant requirements.
What to check: Confirm whether your facility is subject to specific sampling requirements or other pollutant-related conditions. Review your permit coverage and current Ecology guidance rather than assuming the same requirements apply to every industrial site.
7. Permit changes and operational changes aren't reaching the right people
Environmental requirements, site operations, and internal responsibilities can change independently. When those changes aren't communicated, a facility may continue following outdated procedures or overlook an obligation.
What to check: Identify who monitors regulatory developments, who determines whether changes apply, how procedures are updated, and how relevant information reaches facility managers, EHS personnel, and affected employees.
How well is your stormwater program working?
A documented program is important, but reviewing procedures alone may not reveal the full picture.
An effective assessment connects permit requirements with what is happening at the facility: how materials are stored, how drainage systems function, whether controls are maintained, how monitoring results are addressed, and whether employees follow established practices.
For organizations operating multiple facilities across the state of Washington, consistency is another consideration. A common framework can help teams identify gaps, assign accountability, and track corrective actions while accounting for differences in individual sites and permit obligations.
If your facility has expanded, changed operations, experienced recurring monitoring issues, or struggled to keep documentation current, a focused compliance review can help identify where additional attention is needed.
Is your facility's stormwater program ready for scrutiny? Request an EHS compliance discussion to discuss your facility's environmental compliance priorities, identify potential gaps, and determine appropriate next steps.
