On August 7, 2026, Illinois enacted House Bill 4418, directing Illinois EPA to develop and incorporate best management practice requirements for controlling plastic pellets and other preproduction plastic materials (commonly called nurdles) in stormwater runoff under NPDES permits by August 7, 2027. The requirement applies to facilities in the organic chemicals, plastics, and synthetic fibers category and the plastics molding and forming point source category.

This is not the first attempt to regulate preproduction plastic materials in stormwater. The 2021 and proposed 2026 Federal Multi-Sector General Permit — available in the states where EPA is the NPDES permitting authority (Idaho, Massachusetts, New Hampshire, and New Mexico, plus certain federal facilities, tribal lands, and U.S. territories) — requires facilities handling preproduction plastic to implement control measures to eliminate discharges of plastic in stormwater. Covered plastic materials include resin pellets, powders, flakes, additives, regrind, scrap, and waste and recycling streams. California’s State Water Resources Control Board similarly requires plastic manufacturing, handling, and transportation facilities to implement best management practices controlling discharges of preproduction plastics. Cal. Water Code § 13367.

These emerging, plastic pellet-specific discharge requirements are developing alongside Clean Water Act and Resource Conservation and Recovery Act citizen suits alleging unlawful handling and discharge of preproduction plastic materials. Those suits have alleged permit violations, including violations of conditions prohibiting the discharge of “floating solids or visible foam in other than trace amounts,” and unpermitted discharges of “pollutants” under CWA Section 301.

Plastic pellets are a larger form of microplastic and are visible to the naked eye, making them a comparatively feasible target for both regulation and litigation. Facilities that handle plastic pellets should be alert to citizen suit risk and regulatory exposure, and should expect other states to follow Illinois’ lead. Smaller microplastics and nanoplastics may be the next frontier under the Clean Water Act, though likely not until standardized testing, detection, and quantification methods are developed.