As microplastics contamination becomes a growing management concern in California, environmental managers want to know if structural stormwater BMPs have the potential to effectively remove microplastics pollution in urban runoff.

Microplastics, a suspected stormwater contaminant that can enter receiving waters through runoff, was recently identified as a monitoring priority by a statewide panel of scientific experts on CECs (contaminants of emerging concern).

In response, California Sea Grant and the California Ocean Protection Council (OPC) decided in fall 2023 to fund five research projects to improve understanding of microplastic pollution in California, including two projects investigating the potential of stormwater BMPs to reduce microplastics in urban settings.

The SMC is part of one of these solutions-focused projects, with its new Regional BMP Monitoring Network being leveraged by researchers to investigate the extent to which biofiltration and bioretention BMPs across southern California can capture microplastic contamination in runoff.

The other solutions-focused project being funded by Sea Grant and OPC is examining how the design of LID (low-impact development)-type BMPs and characteristics of the surrounding catchment area can influence how these structures retain and release microplastics pollution.

Collectively, the projects will help close knowledge gaps in stormwater management for microplastics that were identified by the California Ocean Protection Council in its Statewide Microplastics Strategy published in 2022.