Microplastics Found Falling With Sierra Nevada Snow
UC Riverside researchers measured plastic particles deposited by snowstorms at seven Sierra Nevada sites, including remote mountain areas.
Updated on Nov. 15, 2026 in Environmental
Live Poll
Are you concerned that microplastics in snow could affect your local drinking water?
Researchers from the University of California, Riverside found microplastics falling with snow across the Sierra Nevada, with snowflakes carrying airborne plastic particles to the ground. The findings raise concerns for California, where Sierra snowpack supplies about 30% of the state's freshwater.
Why it matters
The study points to airborne plastic pollution reaching high mountain snowpack that feeds California's water supply. The study did not determine how much of the pollution reaches drinking water or assess health effects, leaving those questions open for California residents.
The study measured plastic particle deposition through snow sampling at seven sites, with remote locations receiving 270 to 3,200 particles per square meter per day and a site near Mammoth Mountain receiving 2,600 to 7,500, about three times as much. Researchers have not yet determined how much of this pollution reaches drinking water or what health effects it may have.
The players
University of California, Riverside
A public research university in Riverside, California, that is part of the University of California system.
Aleksandra Karapetrova
An environmental toxicologist who collected snow samples at seven Sierra Nevada sites for the study.
The details
Environmental toxicologist Aleksandra Karapetrova collected snow at seven sites, reaching six on skis and one by chairlift. Researchers traced the air masses behind the storms, most of which passed over Fresno and Madera counties, and used infrared light to identify polyethylene, polypropylene and polyester/PET particles. Researchers said nearby human activity and heavier snowfall could help explain the higher amounts at Mammoth Mountain.
Timeline
November 15, 2026: Article published reporting the microplastics-in-snow study findings.
Water Supply Context
Because Sierra Nevada snowpack supplies about 30% of California's freshwater, airborne microplastics deposited on that snow could eventually reach the reservoirs and rivers that the state depends on. The finding adds a new pollution pathway to a water system that already faces drought and snowpack variability.
Californians who rely on Sierra snowmelt for drinking water may eventually see whether microplastic contamination reaches their supply, though the study did not assess that risk. Residents near high-traffic mountain areas such as ski resorts may want to watch for future monitoring results on local water quality.
The takeaway
Airborne microplastics are reaching remote mountain snow, so the pollution question extends beyond cities and roadways to the watersheds California depends on. Follow future water-quality monitoring to see whether these particles reach drinking supplies.
Further reading
Explore more on Environmental coverage for California.
Source note: This article includes information reported by The Tribune.
Live Poll
Are you concerned that microplastics in snow could affect your local drinking water?
