Stormwater as a PFAS Transport Pathway
Municipal separate storm sewer systems (MS4s) collect and discharge stormwater runoff, potentially conveying PFAS from contaminated soils, roads, and firefighting training areas directly to surface waters.
Current Regulatory Framework
The Clean Water Act’s NPDES permitting program regulates stormwater discharges, but PFAS-specific effluent limits for stormwater remain undeveloped at the federal level. EPA’s 2022 PFAS Strategic Roadmap acknowledges stormwater as a priority pathway.
State-Level Stormwater Initiatives
Michigan and New Hampshire have included PFAS in stormwater management plans for MS4 permit holders. California’s State Water Board is developing numeric stormwater quality objectives that may include PFAS threshold concentrations.
Technical Challenges
Stormwater treatment for PFAS is technically complex due to variable flow rates and concentrations. Granular activated carbon and ion exchange systems are being piloted at stormwater outfalls in PFAS-impacted municipalities.