Charles River Algal Blooms Stop Swimming and Launch a Floating Wetland

By Andrew Blok
Environmental Monitor

The Charles River used to be a swimming hotspot for Cambridge and Boston residents.

Decades of industrial pollution and nutrient runoff have degraded water quality and eliminated public swimming in the Lower Charles, but a movement is afoot to get Boston and Cambridge back in the water. One step toward the goal of a safely swimmable river—without the need to obtain a permit, as is now necessary—is detecting and managing the harmful algal blooms that appear on the river.

An experimental floating wetland and new research and analysis of water quality data that shows a possible effective detection system for algal blooms on the Charles River are two new steps toward the goal of safe, accessible swimming.  

Characterizing the Charles River blooms

The EPA has had a monitoring buoy floating on the Charles since 2015. Its publicly available data includes measurements for temperature, specific conductance, pH, dissolved oxygen, and turbidity. It also measures chlorophyll and phycocyanin to gauge the presence and levels of blue-green algae that can release harmful toxins into the river.

Max Rome, a doctoral candidate in the College of Engineering at Northeastern University, has been studying the Charles River’s water quality since 2017. Working with the Charles River Conservancy—a group with the goal of seeing the Charles River healthy and safe for swimming—he studied water quality at one potential swimming site.

“The first step we needed to take was to look at a promising location: What does the water actually look like on a daily basis?” Rome said.

To start, it seemed likely that E. coli and other bacteria would be the biggest issue, but monitoring data revealed they weren’t.

“The river looks pretty decent in terms of bacterial contamination in certain locations,” Rome said. “But the cyanobacteria blooms are a really big problem.”

After gathering a data series of cyanobacteria cell counts, Rome compared them to data collected by the EPA, the Massachusetts Water Resources Authority and the Massachusetts Department of Public Health.

“It was a really fun data analysis project to try and figure out how the sensor outputs correlate with the cell counts,” Rome said.

There were a few surprises.

For one, cyanobacterial cell counts correlated closest with turbidity, not chlorophyll and phycocyanin, measurements from the EPA buoy. They tracked with each other so closely that, for the Charles River, turbidity could be an easy and effective predictor of algal blooms.

The makeup of the blooms bucked expectations as well.

While the findings relate specifically to the Charles River, Rome thinks there are lessons to be learned for measuring cyanobacteria elsewhere.

“That was really interesting to me,” Rome said, “the extent to which cyanobacteria didn’t show up on chlorophyll sensors.”

Similarly, the strong correlation between turbidity and cyanobacteria cell counts shows there are creative ways to monitor water quality and predict harmful algal blooms. A turbidity sensor could be a more affordable entry point to water quality monitoring.

“If you’re a watershed monitoring group, it’s likely something you can afford,” Rome said.

A floating wetland for a swimmable river

Rome is taking another stab at Charles River algal blooms, too.

In 2020 as part of a team that included The Charles River Conservancy and students from local universities, Rome deployed a floating wetland on the river. The project, in part, aims to foster the growth of zooplankton that eat cyanobacteria. The roots of the wetland’s native plants will extend into the water, providing the plankton shelter from predators, allowing them to grow larger and more numerous.

More and larger zooplankton should eat more cyanobacteria.

Floating wetlands are used elsewhere to capture nutrients, like phosphorus, or help filter and purify stormwater runoff.

The floating wetland’s first season was different than expected because of the Covid-19 pandemic. It was deployed in June rather than the beginning of the growing season, but it’s first year was a successful one and proved the design would work with a few tweaks.

Throughout the season, researchers regularly sampled the water beneath the wetland and at a control site to compare zooplankton species and size. The plankton beneath the floating wetland weren’t any larger nor were there more of the larger species the researchers hoped to see.

That might be because the wetland was deployed for shorter than planned and the roots that would serve as zooplankton shelter were only in their first year of growth. Larger, grazing plankton might be present in coming years “as plants become better established and produce a greater root volume,” a report of the group’s findings said.

In 2021, the wetland will get an earlier deployment and researchers will sample for plankton and cyanobacteria five days a week through the summer. If things go as hoped for, this year they’ll find healthy plants, larger zooplankton and a promising method for reducing harmful algal blooms.

The data from this study will inform phase two or the project: a larger wetland that could harbor enough plankton to have a measurable effect on algal bloom development.

It’ll be one step toward a healthier Charles River.

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Can a floating island in the Charles River rescue its water quality?

By Bob Dumas
Boston 25 News

BOSTON — Since early in the summer of 2020, a man-made island has been floating right in the middle of the Charles River.

It’s part of a science experiment focused on curtailing harmful algae blooms.

The small island, which sits in the shadow of the Longfellow Bridge, is designed to replicate a local wetland.

It’s about 700 square feet, the size of a typical one-bedroom apartment. It has 3,000 plants, representing about two dozen species native to New England, covering the structure, which is comprised of 24 interlocking pieces.

“The floating wetland is an experiment,” explained Laura Jasinski, Executive Director of the Charles River Conservancy. “It’s a pilot program to study how adding good ecology back to the river could make the Charles more adaptable and fight the algae blooms.”

Algae blooms are harmful to people because they release toxins which can cause skin irritations or more serious problems if ingested. Pets can also suffer health problems when exposed.

The Charles River Conservancy is focused on getting the water quality in the river to the point that people can regularly swim in it.

Jasinski said great strides have been made over the last 30 years.

“The EPA has a grading system for the river. In 1990, we were at a D, almost a failing grade. As early as 2017, we were at an A-,” she said.

Paul McDougall grew up in Cambridge and remembers swimming and skating on the Charles River.

“You go back the 50s and 60s, you had a lot of industry going on,” he explained. “Of course, back then that’s where they dumped all their excess chemicals and things.”

Those days may be long gone, but the algae blooms are now becoming more frequent, due to increasing water temperatures and storm runoff.

The floating wetland is a novel experiment, looking at a new way to control the algae, according to Max Rome, a PH.D. student at Northeastern University. He says the natural food chain has broken down over the years which has allowed the algae to flourish.

Today, a natural predator for the algae has a hard time thriving in the Charles River basin.

Rome is testing whether this floating wetland gives these organisms, known as zoo plankton, a better chance at surviving.

When the island was built last spring, it was designed to be porous, allowing the roots of the plants to dangle in the water, providing a habitat for the zoo plankton.

“Some people who study these algal blooms kind of consider these algal blooms and this type of water pollution to be the biggest water quality issue in the world right now,” said Rome. “This type of solution is super applicable to any urban water body, any developed water body, where re-establishing wetlands is difficult.”

The experiment in the Charles River will last two years.

Jasinski hopes it will ultimately make her dream of a swim-able Charles River a reality.

“It’s really exciting to think about what a fully usable Charles River could be for Boston and Cambridge,” she said. “A lot of people have to go to a public pool or drive a significant distance to get to a beach or a natural body of water.”

Algae blooms are popping up in other parts of the state. For example, some of Cape Cod’s freshwater ponds have been repeatedly closed due to algae blooms.

Swimming area proposed on Charles

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Artificial Island Launched Into Charles River To Improve Local Ecosystem

WBZ NewsRadio

The first human-made island is 700 square feet and located just past the Longfellow Bridge, in the Charles River basin.

Laura Jasinski is the executive director of the Charles River Conservancy. She told WBZ NewsRadio’s Chris Fama’s why the nonprofit decided to create the island and drop it off into the Charles River.

“To bolster the natural ecology of the river,” Jasinksi said. It’s also important to remove the harmful algae blooms that have been growing in the river.

“That algae can be harmful to humans and pets if they get near it or touch it,” Jasinksi said. “So we’re looking at a new way to try to help combat that issue.”

The island contains over 3,000 different plants.

WBZ NewsRadio’s Chris Fama (@CFamaWBZ) reports

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Charles River Conservancy, Northeastern University announce floating wetland project

Cambridge Chronicle

The Charles River Conservancy and Northeastern University’s department of civil and environmental engineering, in partnership with Foth, an engineering consulting firm, and the Massachusetts Department of Conservation and Recreation, have announced the installation of a floating research wetland in the Charles River designed to explore an ecological approach to further improve water quality.

Planted with more than 15 native wetland species, this 700-square-foot, human- made island is the first of its kind in the Charles River basin and a model for resiliency projects across the commonwealth. It will be located downstream of the Longfellow Bridge, near the mouth of the Broad Canal.

Born from the Charles River Conservancy’s Charles River Swimming Initiative, this project aims to build on the EPA’s Charles River Initiative and the dedication of governments, environmental groups and nonprofits to improve the Charles River and focus on the growing threat of harmful algal blooms.

“From our Swim Park Feasibility Study and subsequent daily water quality monitoring at North Point Park for two summers, we learned that local bacteria levels have improved to where swimming could be allowed on most days in the summer,” said CRC Executive Director Laura Jasinski. “However, algae blooms, which are fed by rising temperatures and stormwater runoff, can release harmful toxins and are a growing barrier to swimming. To take full advantage of all the Charles River has to offer, we need to address these climate change realities. Climate adaptation pilot projects, like the floating wetland, are an important first step.”

The Charles River floating wetland project continues a multi-year partnership with NU-CEE PhD student Max Rome, who also led the monitoring program at North Point.

“While development along the Charles has fundamentally changed the river’s ecology, there are lessons we can learn from its original state and nature’s inherent resiliency,” said Rome. “This floating wetland project provides an important opportunity to study how the wetland can bolster zooplankton populations, a natural predator of algae.”

Foth has also been a “critically important member” of the project team. The firm has provided pro-bono services along with knowledge of Charles River and marine engineering projects.

“This project has posed some unique design challenges,” said Scott Skuncik. “We are excited to be a part of this important research effort that reflects our company’s commitment to sustainability.”

“The Charles River is an incredible natural resource situated within the heart of the greater Boston metro area offering visitors with a high level of access to state parkland and recreational opportunities,” said department of conservation and recreation commissioner Jim Montgomery. “DCR works closely with stakeholders and organizations, such as the Charles River Conservancy, in an effort to foster strong partnerships and encourage shared stewardship throughout the state parks system.”

“Protecting Massachusetts’ unique natural resources, like the Charles River, is an essential part of the Baker-Polito Administration’s strategy to mitigate and adapt to the impacts of climate change,” said energy and environmental affairs secretary Kathleen Theoharides. “Building meaningful partnerships at the local level to help identify vulnerabilities and develop innovative solutions is critical to our success, and I applaud the Charles River Conservancy for their work on this project, which provides an important model for future adaptation efforts across the commonwealth.”

For the Charles River Conservancy, using the floating wetland to “increase environmental literacy” is fundamental to their mission and one of the main project goals.

“The floating wetland not only provides an opportunity for research but also a focal point for engagement around the river’s ecology. Many people still think of the Charles as dirty. That is no longer true, but we still have work to do,” said Jasinski. “Although some research and activities related to the floating island have been affected by COVID-19, the CRC is continuing to work with partners to provide opportunities to learn about the wetland. “Keep a lookout for a video game created by students at Cambridge Rindge and Latin High School and, hopefully soon, kayak tours.”

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Artificial island launched in Charles River; researchers hope it will help clean the water

By Matt Berg

Workers prepared the artificial island Tuesday. The theory is that it will become home to tiny organisms that eat the harmful algae that blooms in late summer in the river. DAVID L. RYAN/GLOBE STAFF

In the latest effort to rid the Charles River of its notoriously “dirty water,” conservationists launched an artificial island full of native plants Tuesday afternoon to study whether it could reduce harmful algae blooms.

Members of the Charles River Conservancy, a group that has worked to maintain the river and its parks for decades, have visions of people swimming in the water on a sweltering summer day, or fishing with friends. They dream of restoring the river to pre-development days.

“So many people still think of it as ‘that dirty water,’ and we’ve made a lot of progress,” said Laura Jasinski, executive director of the Charles River Conservancy. “But we still have new challenges.”

Over the course of two years, scientists will study the effect the 700-square-foot floating wetland has on the river’s water quality. The island, home to 15 native wetland species, was launched near the Longfellow Bridge by the mouth of the Broad Canal Tuesday afternoon.

After collecting water samples from North Point Park along the Charles in years past, “we learned that bacteria levels were at a level where you could swim the vast majority of time in summer, but the problem is with algae blooms” in the late summer, Jasinski said.

The algae bloom predicament “is getting worse, and that’s what’s most concerning,” she said. “They’re hard to predict.”

Algae blooms are overgrowths of algae that can produce dangerous toxins. Nutrients in runoff from surrounding impermeable surfaces, such as pavement and roads, combined with high temperatures in the summer, cause the blooms to peak in July and August, Jasinski said.

The theory is that the island could create a home base for tiny organisms that eat the algae.

“What we’re going to study is how it creates a habitat for zooplankton, the natural predator of algae,” she said.

“While development along the Charles has fundamentally changed the river’s ecology, there are lessons we can learn from its original state,” Max Rome, a doctoral student in engineering at Northeastern University who is working on the project, said in a statement.

If researchers discover a noticeable difference in water quality, several islands may be launched in years to come. It’s hard to say what that might look like, but Jasinski imagines one possibility: an area surrounded by islands, allowing for especially clean water and a designated swimming area.

Along with other data collected from the island, “We would like to understand the effect of proximity of the islands. Could you surround a swimming area with these? How many would there need to be?” Jasinski said.

Although it can technically support the weight of humans, the island is not open to the public, she said. Those who want to get a close look can do so from kayaks or the bridge.

She invited people curious about conservation efforts to take a look at resources on the organization’s website.

“We want to engage people in understanding the river,” Jasinski said. “It’s complicated to understand all of the water science, but we want to make it more accessible to people.”

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The Charles Has Sprouted A New ‘Island’

By Craig LeMoult

The “floating wetland” in the Charles River. Craig LeMoult/WGBH News

On Tuesday afternoon, a team bolted together two dozen large structures off Magazine Beach in Cambridge, assembling an island like a floating puzzle.

“It’s a seven hundred square foot, human-made island, planted with 3,000 native wetland plants that we are about to tow down the river to just past the Longfellow Bridge, where it will be anchored,” said Laura Jasinski, executive director of the Charles River Conservancy.

The floating wetland is part of a research project aimed at improving the water quality by cutting down on toxic blooms of algae called cyanobacteria that have become an annual summer problem in the Charles.

The project will restore a bit of nature to an area of the river that doesn’t feel all that natural now.

“Where this is going to be, it’s a bulkhead or sea wall,” Jasinski said. “So we don’t have a river bank the way we’re used to in that area. So we’re trying to add that back, effectively, to try to boost the food chain and the river to help it be more adaptable to changing conditions.”

Jasinkski rattled off a list of the 22 native plant species planted on the floating island.

“So we have things like Rose mallow and Sweet flag, Swamp milkweed, Seaside goldenrod, Spotted Joe Pye, Monkey flower,” she said. “So lots of lots of fun things.”

Over time, the roots of the plants will penetrate the structure, creating a hydroponic garden. The floating wetland be there for two years as researchers study what happens around those roots.

“This project is all about understanding what we can do from ecological perspective to kind of help create a river that’s healthy and doesn’t have cyanobacteria blooms,” said Northeastern University PhD student Max Rome, who’s leading that research.

Those toxic blooms have become an annual problem in the Charles.

“What we’ve been seeing… is very distinct blooms that last for about seven to 14 days,” Rome said. “And it tends to occur as the water temperature reaches about 25 degrees Celsius, 77 degrees Fahrenheit. And that usually happens in late July or August.”

Rome says one way to fight cyanobacteria is by cutting pollution.

“But we think another piece that might be important is to add habitat that can help the river support higher population of the creatures that eat algae.”

Those creatures are called zooplankton. Rome will track if the floating island results in more and larger zooplankton around the roots of the plants that grow down into the river.

“It’s going answer some really fundamental questions for us about how the ecosystem changes around the floating wetland,” Rome said. “And then with that data, we’re going to be able to do some modeling and do some estimation to see at what scale could floating wetlands or restored shoreline really make an impact in terms of cleaning up the Charles River.”

Jasinski says the cyanobacteria outbreaks are only expected to get worse as temperatures rise.

“The reason we’re seeing the increased algae blooms in the river is a symptom of the rising temperatures of climate change,” she said. “So we’re looking [at this project] as an intervention to help treat that.”

And she says she hopes as people see the island, it will serve as a way to engage people in those issues.

“We really want to use this as a platform to talk to people about how polluted [the Charles River] was, how far we’ve come, but also the increasing challenges we’re seeing with climate change, rising temperatures, increased heavy rainfall that is still posing a threat to the river that we need to continue to innovate and try to protect.”

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Babylon had its hanging gardens; one day the Charles River basin could have floating gardens

By adamg

The Charles River Conservancy hopes to install a “floating wetlands” at North Point Park next spring to test whether the reintroduction of wetlands to the Charles River basin could shield enough microscopic animals to eat and so control the bacteria that now sometimes turn that stretch of river into a hazard to both man and beast.

Working with Northeastern PhD candidate Max Rome and the Penelope Taylor Studio, the group would install a roughly 700-square-foot floating platform to plant a variety of wetlands plants to determine whether that could be used to shield zooplankton from the fish that have been increasingly drawn to the Charles as its water quality improves.

The floating wetland will be planted with over 20 native wetland species. Plants like rose mallow, cardinal flower, and milkweed will be arranged to create a unique floating garden, an attraction for human and non-human visitors. Throughout our study, we will monitor the plants to understand which species succeed in this novel environment.

If it works, the zooplankton in turn could begin to devour the cyanobacteria, also known as blue-green algae, that now can explode in numbers, creating toxic blooms that can kill dogs that swim in the river and make people sick.

The small platform itself would have no noticeable effect on the overall basin, the group says, but proof of its success could be the impetus to install far more of the platforms – or to plant more permanent wetlands vegetation in what has long been more of a lake than a river, one that, despite clean-up efforts over recent decades, remains chock full of the phosphorus that encourages the growth of the bacteria.

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