Microplastics in the Chesapeake: Report finds contaminants in Maryland waterways

A small-scale study from the advocacy group Environment America found evidence of microplastics throughout the Chesapeake Bay watershed, the group announced Tuesday.

Using citizen scientists, the group collected several water samples at 15 different places throughout the watershed, including five sites in Maryland waterways. They found microplastics at every site, whether in the form of plastic fiber, film, beads or fragments.

“Plastic pollution is pervasive, and it’s a danger that’s not just out there in some patch across the ocean. It’s right here. It’s knocking at our front door,” said Baltimore Harbor waterkeeper Alice Volpitta during a news conference Tuesday along the Baltimore waterfront.

The results, according to several local environmental groups, are strong evidence that Maryland lawmakers should move forward with legislation this year to curb plastic pollution, including a bottle return program that would reimburse Marylanders who drop off plastic drink containers for recycling.

The environmental groups unveiled the report Tuesday beside Mr. Trash Wheel, one of the four anthropomorphized trash-collecting machines installed around the Baltimore Harbor by the city’s Waterfront Partnership.

In 2025 alone, the four wheels collected 768,000 pounds of garage and debris from the city’s waterways, said Allison Blood, senior manager of environmental projects and advocacy at the Waterfront Partnership.

“While that’s an impressive accomplishment, we know that cleaning up the pollution downstream is not a long-term solution. We need to turn off the tap upstream,” Blood said.

Microplastics are particularly insidious because their small size — less than 5 millimeters, or about the size of a sesame seed — means they aren’t easily collected by the wheels.

“Unlike an apple or piece of paper that will decompose gradually over time, plastic breaks down into smaller and smaller pieces of plastic,” said Nina Harbison, an associate at Maryland PIRG, a sister organization to Environment America.

Once they enter the ecosystem, these microplastics are often consumed by fish and other wildlife, causing a host of health issues. Microplastics can attract and carry pollutants found in the water, and release chemical pollutants of their own, according to the National Oceanic and Atmospheric Administration. Plastics and their associated chemicals can delay developmental stages, hinder reproduction and make it more difficult for animals to fight disease, according to the agency.

Microplastics have also been found in the human body, and some studies have associated them with a greater risk of human health problems. For instance, in a study of patients with plaque buildup in their arteries, patients with microplastics in plaque had a higher risk of heart attack, stroke, or death.

The study from Environment America tracked microplastics at Maryland sites along the Patapsco, Choptank, Nanticoke and Susquehanna rivers — and in the Chesapeake Bay itself near Talbot County. Lab researchers also analyzed samples from sites in Washington, D.C., Virginia, Pennsylvania and New York.

All of the sites contained plastic microfibers, 93% of them contained microfragments, 47% had microfilm and 27% had microbeads.

There is no “silver bullet solution” for addressing the “mini menace” of microplastics, Harbison said. But PIRG is among the groups that think a bottle return system would go a long way in Maryland.

Maryland’s “bottle bill,” as it’s known, has been introduced repeatedly in the Maryland General Assembly. The current iteration has been introduced in each of the past four years, but has yet to receive approval from the full House or Senate.

Under the bill, plastic producers would contribute funds to operate the program, which would be overseen by the Maryland Department of the Environment.

Meanwhile, environmental groups point to other wins, including 2025’s passage of broader “extended producer responsibility” in Maryland, requiring various packaging producers to pay fees that help cover the cost of recycling the materials.

In 2015, Maryland enacted a ban on “synthetic plastic microbeads,” in personal care products and over-the-counter drugs, which were added to rinse-off personal care products for exfoliation or cleansing purposes.

Maryland has also taken action on other harmful packaging materials. Beginning in 2020, Maryland banned most uses of polystyrene, also known by the brand name Styrofoam.

Since the ban took effect, Baltimore’s Waterfront Partnership has seen an 83% reduction in polystyrene collected by its trash wheels, Blood said. Similarly, the partnership has noted a 55% reduction in plastic bag pollution collected by the wheels, after a local plastic bag ban.

“These reductions demonstrate that policies can prevent plastic pollution from reaching our waterways in the first place,” Blood said.