The National Park Service website said that the restoration of the river has been “remarkable” but “fish consumption” is not advised. The stream is good for canoeing and kayaking but swimming is not recommended.

“I found out that this was one of the most polluted rivers in America,” senior Clover Burke said. “It used to be one of the top 10. And that you should only eat one fish max per year from this river because of the amount of heavy metals. Or else it’s really bad for you.”

In 1971, Audubon magazine said the river was “one of America’s most polluted rivers.” In 1990, the Environmental Protection Agency said the river held “toxic sediments” left by textile and metal industries during the second half of the 19th century, leaving communities to deal with environmental issues.

“It’s awful,” Burke said. “It’s insane that a river that should be for everyone, including all the animals, you can’t even eat from.”

According to the park service, non-point pollution (runoff dispersed from many sources) is now a major threat to the river, including “reckless excavation practices, uncontrolled stormwater runoff, and certain landscaping.”

The NPS said runoff carries nutrients into the cola-colored river, causing harmful algal blooms that muddle the ecosystem. This affects surface and groundwater quality.

Frequent downpours have led to historic flooding in December and January, and recent heavy rains nearly led to the cancellation of the field trip, AP environmental science and biology teacher Amy O’Donnell said.

The trip was funded by the NASA Rhode Island Space Grant, funds that the space agency distributes to every state to engage students in STEM.

Brown University distributes the funds to K-12 schools around the state.

Ralph Milliken, associate professor of Earth, environmental, and planetary sciences at Brown, said O’Donnell’s application was picked because the university felt it was a trip that would leave a lasting impression on the students.

Milliken said that in addition to flinging rockets into space, NASA has a big Earth science program.

“We want to get students outside the classroom beyond the textbooks and internet articles they read about” he said. “So they can understand the interplay on human society and the natural environment.”

In addition to supporting local schools, Brown has offered internships for students at NASA centers, hosted students at on campus for the April total solar eclipse, and partnered with WaterFire for a program on the sea-level rise.

Brown receives $860,000 each year for the statewide program but that number is expected to be cut to $800,000, Milliken said.

Milliken said schools can apply for science education funding by contacting the university with their ideas.

“Now and then we learn about climate change — we’re looking at evidence of climate change here,” O’Donnell said standing on several feet of sand deposited by recent floods. It will make it more difficult for native species to grow.

When the river swells, it also uncovers evidence of the land’s previous use as a dump.

“All this is pretty worrisome, especially being able to go out and see it firsthand,” junior Preston Brown said. “It’s a big issue because we’re going to be the ones that are dealing with it.”

Brown learned about the presence of an invasive plant called Japanese knotweed that also grows in the woods behind his house.

“I want to be able to enjoy the forest, so I’m taking this class to learn how to save it,” he said.

Advertisement

Junior Taejo Chung-Brcak said “mountains of trash” pile up near his yard from street-level pollution after a deluge. Science isn’t his favorite subject, but the field trip was eye-opening for him.

“My teacher makes it interesting and makes nature seem like something worth fighting for,” Chung-Brcak said.

O’Donnell and Diane Siliezar-Shields, teacher and science department chairperson at Barrington High School, modeled the class after environmental activist Rachel Carson, whose 1962 book “Silent Spring” showed the world the danger of forever chemicals — extremely persistent chemicals that last thousands of years — found in the water, and the blood of nearly 97 percent of Americans, according to the National Institute of Environmental Health Sciences.

Carson’s work led to a ban on DDT (Dichlorodiphenyltrichloroethane) and is credited for the creation of the EPA.

O’Donnell said she is teaching her students to be “problem solvers” who invest in their local environment before they graduate.

“We have a curriculum that is really heavy duty,” she said. “We want to show our young people there is hope. If you leverage your understanding and activate yourself, you build a community around yourself, which I think is perfect. There’s so much time spent on computers now, I wanted them to really be able to see this firsthand.”

O’Donnell said staff at Friends of the Blackstone showed the students how bioremediation can be used to fight pollution naturally.

“We planted willows to be able to clean up the soil,” she said.

John Marsland, president and founder of Friends of the Blackstone, said the willows work to absorb heavy metals in the soil. The willows can also thrive despite the sandy silt left on shore by floodwaters.

“We planted the native willows to re-establish native trees on the flood plain instead of knotweed,” Marsland said. “We mow the knotweed three times a year and plant grass but there’s so much sand from the flooding, it’s almost a foot deep. I don’t think grass will grow. Willow can.”

Advertisement

Students hammered posts 2 feet into the soil and planted rows of willow tree branches.

Burke said she is going to study forestry and environmental science after high school. She wants to help fix the problems caused by people.

“I get to go home and tell my parents random facts and they think I’m so smart,” Burke joked. “But this is, I feel, a class everyone needs to take to know the basics about our environment.”

Junior Sofia Buchanan has been working on a project on microplastic awareness. Sophomore Iris Yang said the class has taught her to be aware of the nature around her. Sophomore Claudia Leonard said she’s learned how to decrease pollution in the environment.

“I see the plastic as kind of a warning of what will persist in the ecosystem 50 years later if we currently don’t come up with solutions because right now we’re already seeing plastic in the rivers. And, we’re seeing the health effects of pollution on the ecosystem and ourselves.

“I think that this is a warning for what pollution could do to humans in the future and other animals.”

Carlos Muñoz can be reached at carlos.munoz@globe.com. Follow him @ReadCarlos and on Instagram @Carlosbrknews.