Published May 13, 2026 at 6:00 AM MDT

Earning a spot on the Colorado School of Mines microplastics sampling team on the South Platte River requires careful balancing in waist-deep water and occasionally dodging some very inquisitive Canada Geese.

Standing amidst the honking geese and clouds of tiny aquatic insects on Friday, students on the team held onto a 20-foot-net as they collected samples from a stretch of the Platte in South Denver near Grant-Frontier Park.

When the samples go back to the lab, the students will be able to see some of the harmful microscopic items that are hiding in the urban waterway.

“A lot of microplastic research right now focuses on drinking water, or how we’re consuming microplastics, but urban rivers are a secondary way of exposure for a lot of people,” said Mines PHD candidate Anne Marie Mozrall. “Exposure for a lot of people is through swimming in it, just interacting with the water. Urban rivers also see a lot of pollution, because there's a lot of people around them.”

Mozrall said her research project is focusing on the South Platte because there hasn’t been a lot of microplastic data collected so far from it.

Scott Franz/KUNC

A group of Colorado School of Mines students hold a net in the South Platte River while they collect samples for microplastics.

Microplastics in rivers can hurt wildlife and transport harmful pathogens. Mozrall says early samples from the South Platte have revealed two surprises. They’re finding lots of debris from bike and car tires. And fibers from people’s clothes.

“I think it’s astonishing,” master's student Elsa Scherzinger said. “Every time we’re in the lab…I’m just shocked by the amount and diversity of microplastics that we find.

Mozrall said her team’s samples will be analyzed and compared to other urban river systems around the country and the Caribbean. Other sampling has taken place in the Dominican Republic.

“We wanted to sample two very different sites to kind of see how their micro plastic levels differ, and look at some of those differences, like population density, waste management, infrastructure and presence of macro plastics to see if we can find any sort of correlations,” she said.

Learn more about the program.