Washington ISGP Requirements for Ports and Industrial Sites

What the ISGP Requires From Ports and Industrial Facilities

Washington’s Industrial Stormwater General Permit requires covered industrial sites to sample discharge, maintain a Stormwater Pollution Prevention Plan, and respond to benchmark exceedances on a set timeline. Coverage generally applies where industrial activity is exposed to stormwater that discharges to surface waters or a connected storm drain.

For port operations along Puget Sound, metals such as zinc and copper remain important stormwater pollutants, particularly where cargo handling, heavy equipment, and vehicle traffic expose paved industrial areas to rainfall.

Miss a sampling window or corrective action deadline, and a facility can quickly fall behind on compliance. Washington Stormwater’s team brings more than 20 years of experience working on construction, industrial, and civil sites across Washington.

Key Takeaways

• A benchmark exceedance under the ISGP starts a three-level corrective action clock, and the first response is due within 14 days.
• Zinc and copper are important pollutants for many marine cargo and port operations, particularly where heavy equipment, vehicle traffic, galvanized materials, and outdoor material handling are exposed to stormwater.
• Ecology has proposed moving the ISGP’s expiration date from December 31, 2029 to December 31, 2028, with public comment open through October 2, 2026.
• Commercial, industrial, and multi-story residential buildings built or renovated between 1950 and 1980 may contain PCB-containing materials that require additional precautions before exterior washing or other work that could release PCBs to stormwater.
• A site may be exempt from ISGP coverage if its stormwater does not discharge to surface waters or a connected storm drain. Facilities with industrial materials and activities completely protected from stormwater may instead qualify for a Conditional No Exposure exemption.

Who Needs ISGP Coverage at a Washington Port or Industrial Site

Facility Types the Permit Covers

The ISGP folds a wide range of Washington operations into one framework. Marine cargo terminals, log yards, vehicle recyclers, and manufacturing plants all fall under the same coverage requirement once outdoor activity touches stormwater. According to the Washington State Department of Ecology, most industrial sites statewide need coverage under the Clean Water Act and state water pollution law.

Ports and waterfront facilities face particular scrutiny. Cargo handling, container storage, and vessel maintenance all generate runoff that mixes with rain before reaching Puget Sound. A facility running industrial water treatment alongside its stormwater program often finds the same contaminants in both discharge streams. Process wastewater and site runoff frequently share the same sources on a busy industrial property, which is why a single compliance plan should cover both rather than treating them as separate problems.

When a Site Can Skip Coverage

Not every facility with outdoor operations needs ISGP coverage. A site can qualify for a Conditional No Exposure exemption if its industrial materials and activities are completely protected from exposure to stormwater and the facility meets Ecology’s CNE criteria. Few port or heavy industrial operations meet that bar, since cargo, containers, and vehicles typically sit outside for part of their handling cycle.

Facilities that assume they qualify without confirming it in writing risk discharging without coverage. That mistake carries its own penalties, separate from any benchmark violation. Ecology expects a signed certification on file, not an internal assumption, and it needs updating whenever site operations change enough to expose new activity to rain.

Sampling and Benchmark Requirements Under the ISGP

Pollutants Ports Watch Most Closely

Port and marine terminal sites answer for a pollutant mix shaped by their operations. Zinc and copper are common concerns, driven by galvanized container coatings, brake wear on cargo handling equipment, and heavy vehicle traffic across paved yards. Both metals exist in dissolved and particulate forms. A filtration system built for sediment alone will miss a meaningful share of what a benchmark sample catches.

Fueling areas and equipment maintenance bays can also contribute petroleum hydrocarbons to stormwater. Sites should sample and evaluate their own discharge to confirm which parameters need attention, since the pollutant mix varies by operation.

What Happens After a Benchmark Exceedance

Ecology built the ISGP around a three-level corrective action framework, as the Northwest Seaport Alliance’s stormwater guidance outlines. Each level escalates what a facility must do. A first benchmark exceedance triggers Level 1 corrective action. Within 14 days, the facility must investigate the cause, inspect the site, and evaluate whether changes to the SWPPP and operational source-control BMPs are needed.

A second quarterly exceedance for the same parameter within a calendar year triggers Level 2 corrective action and calls for structural source-control BMPs. A third quarterly exceedance for the same parameter within the calendar year triggers Level 3 corrective action, which can require treatment technology such as active filtration or electrocoagulation. Once a facility works through a Level 2 or Level 3 response, further exceedances of that parameter in the following calendar year do not restart the clock.

Building SWPPPs and BMPs That Hold Up to Inspection

Matching BMPs to What a Site Actually Does

A written Stormwater Pollution Prevention Plan only works if its practices match what actually happens on site. Washington Stormwater routinely treats construction stormwater with a pH exceeding 12 during vault and wall construction. That condition shows up often on the same industrial and heavy civil sites that later fall under ISGP monitoring. The experience carries over directly, since port and industrial work sees similar pH swings and metals loading once concrete, coatings, and heavy equipment enter the picture.

Field crews who show up only after a benchmark exceedance are working from behind. Facilities get more value from a partner who checks catch basins, sediment traps, and BMP placement before Ecology’s sampling window opens. Mobilization speed matters too, since a 14 day corrective action deadline leaves little room for a slow response. A crew that can reach a site within 36 hours turns that narrow window into a manageable task.

Treatment Options That Fit Port and Industrial Sites

Matching System Size to Flow and Contaminant Load

Port and industrial sites rarely need the same treatment footprint twice. A container yard shedding heavy sediment and metals calls for a different setup than a manufacturing site with a smaller pH-only discharge. Washington Stormwater builds across that range, from a 50 to 75 gallon per minute unit on a 12,000 pound trailer to a roughly 150 gallon per minute system on a gooseneck trailer for higher flows. Smaller sites sometimes need only pH correction, which fits inside an enclosure as compact as an 8 by 10 inch tool box.

On-Site Systems Built for Fast Deployment

A treatment system that cannot reach a site quickly does not help much once a Level 1 clock starts running. Trailer-mounted systems move between job sites without a lengthy setup process. That matters on a port property, where equipment often needs to relocate as cargo operations shift. Washington Stormwater has supplied similar mobile systems for state transportation projects, including a unit built to WSDOT specifications.

A system that arrives already sized to a site’s flow rate saves money too. It spares a facility the cost of downtime while a treatment plan gets adjusted on the fly.

New Compliance Wrinkles for 2026 and Beyond

PCB Precautions for Older Buildings

Facilities planning exterior pressure washing, surface preparation, painting, or renovation work should build in an added screening step. Buildings constructed or renovated between 1950 and 1980 may contain PCB-containing materials, particularly multi-story residential, commercial, and industrial structures, according to Washington Department of Ecology guidance. Pressure washing can move PCBs from these materials into stormwater, so Ecology advises against pressure-washing a building that may contain PCBs unless BMPs are in place and all wash water is collected rather than allowed to reach a storm drain.

Facilities with older port or industrial buildings should identify and appropriately manage suspected PCB-containing materials before exterior washing, surface preparation, renovation, or other work that could disturb those materials. Older port infrastructure and industrial buildings built during that window face this more often than newer construction. Terminal warehouses and cargo sheds from that era were rarely built with today’s coatings in mind.

A Shorter Runway Than Originally Planned

The current ISGP took effect January 1, 2025, and was set to run through December 31, 2029. Ecology has since proposed a modification that would move the expiration date up to December 31, 2028. The agency is taking public comment on that change through early October 2026.

Facilities that budgeted compliance planning around the original 2029 date should build in a buffer. A shorter permit term means a shorter runway to plan for whatever new sampling parameters or benchmark values show up in the next reissuance. Ports and industrial sites that wait until a new permit is final to start adjusting their SWPPP usually end up rushing that update under a tighter deadline than they expected.

Final Thoughts

Skip a Level 1 corrective action deadline, and a facility risks more than a warning letter. Ecology can escalate to formal enforcement, and a documented pattern of missed deadlines follows a site into its next permit cycle. For a port or industrial facility handling cargo, chemicals, or heavy equipment near Puget Sound, that history makes every future inspection harder.

Washington Stormwater works with construction, industrial, and civil infrastructure clients across King, Pierce, and Snohomish counties, including port and marine terminal facilities. The goal is to keep stormwater programs practical instead of reactive, from SWPPP development through on-site sampling and treatment. A facility that treats compliance as an ongoing routine avoids most of the deadlines that trip up everyone else.

Frequently Asked Questions