by Vivek Hv

“Well I love that dirty water

Oh, Boston, you’re my home”

“My first memory of the Charles River is of a song we had growing up – it was love that Dirty water, Oh Boston, you’re my home,” said Susan, a long-time resident of Cambridge, Massachusetts, as she let out a guffaw. That evening, I sat down with her to learn more about a river I was writing about.

In 1966, the Standells released a single titled “Dirty Water”–an ode to Boston and the Charles. Most Bostonians know this song well. The song is now played as a victory anthem for the Boston sports teams. 

However, I came to these shores only two years ago, and my first memory of the Charles is very different. I remember waking up in the middle of the night, severely jet-lagged, to see a beautiful river reflecting the lights on the bridge as it flowed silently away.

“It’s magical, isn’t it?” said Susan when I recounted my first memory. “Maybe around 2008. That’s when I joined Community Rowing. I liked it most when I was a coxswain–I could see ahead of me. I could see the lights on the bridges reflecting in the water. It was magical. That started to tell me that I could develop a sense of home here.”

Over the last couple of years, I have remarked at the river numerous times. The water always looks pristine and inviting. Yet I also recall, during different conversations, how filthy or how unsuitable the river was to swim in. 

So when the opportunity arose to write this piece about a charming river with a murky past and possibly murkier depths, I felt as if I had a mystery to solve.


Figure 1: Course of the Charles River. The river starts in the small town of Hopkinton – also the starting point of the Boston Marathon – and flows westward in a meandering fashion through more than 35 municipalities and finally into the Atlantic.

Massachusetts was one among the many Native-American tribes that called the bay and the river their home. Quinobequin–“meandering” or “tortuous”–was the name they gave the river we call Charles.

The story has it that Captain John Smith originally named the river the Massachusetts River, after the tribe that lived by it. When the map was presented to King Charles I, the king was encouraged to change any of the “barbarous” names to “English”.

King Charles seized that opportunity.

Three small streams start near Hopkinton, some 26 miles away from Boston, to converge in the man-made Echo Lake to form the source of Charles River (Figure 1). Hopkinton is also where the Boston Marathon begins. But unlike the marathon, the Charles River twists and turns for about 80 miles before it flows into the Atlantic.

And it takes its sweet time. The river drops only about 350 feet (the mean sea level near its source is around 385 feet), which results in a slow flow. A slow flow tends to drag more sediment with it and hence the waters will always look brownish–no matter how clean. The relatively small watershed–the area of land that drains into a river/lake/ocean–of the Charles is about 300 sq. miles, covering over 35 towns and cities.

If the Massachusetts tribe saw the river today, they would barely recognize it. However, they would probably find solace in the fact that Quinobequin remains as meandering as it was back then.

“The Charles River has been dirty forever”

Bob (Robert) Zimmerman recalled his first tryst with the Charles. Bob (Robert) Zimmerman has spent the last 28 years–from 1990 to 2018, a period that saw significant changes to the quality of water in the Charles–as the executive chairman of the Charles River Watershed Association (CRWA). I caught up with Bob, now retired, at a cafe in Alewife.

When Bob joined the CRWA in 1990, many in the city and beyond were convinced that the river was beyond saving. “I believe this is a direct quote: ‘The Charles River has been dirty forever’,” said Bob as he recalled one of his early meetings at the Massachusetts Water Resources Authority (MWRA).

Over the preceding  200 years, the river’s condition had severely deteriorated.  It had been an outlet for effluents from the mills in the 1800s, then the Watertown Arsenal from the late 1800s to1960s. However, the most significant of the reasons why the Charles was dirty was unregulated Combined Sewage Overflows. 

Combined sewers are sewage collection systems that collect both surface runoff and sewage water at the same time to be transported to water treatment plants. In the early 1900s, as roads and pavement construction increased significantly, there was a significant increase in rainwater runoff. Roads and pavements are impervious surfaces and much less of the rainwater is absorbed into the soil underneath. This put immense pressure on the pipes of the sewage system, as they were not designed for the higher capacities. This led to increased instances of sewage water backing up onto streets and basements, causing public health issues.  

Combined Sewage Overflows, or CSOs, were a clever solution to this problem (Figure 2). Adopted by many cities, including Boston, they relied on a simple mechanism where, during times of increased runoff (eg. during rainfall), excess sewage would be allowed to flow directly into a body of water. In the case of Boston, this was the Charles River. 

An uncontrolled increase in CSOs meant that a supposed solution to the sewage problem quickly became the largest source of pollution in the river. In the first five decades of the 20th century, the river had had barely any time to adjust to the buoyant economy that it supported. 

And so by 1966, the river was dirty enough that someone decided to write a song about it. “The Standells in 1966! Yes, I bought the album when I was 16 years old,” Bob recalled his first tryst with the Charles.

Figure 2: Sources of Pollution in the Charles River. There are three significant sources of pollution in the Charles River: (1) Combined Sewage Overflows (CSOs) allow outflow of untreated sewage directly into the Charles River during rainfall. (2) Groundwater runoff from impermeable surfaces like roads and pavements often contains dangerous amounts of nutrients that can cause harmful cyanobacteria blooms in which cyanobacteria thrive. (3) Industrial and commercial effluents from industries (e.g. mills, boat houses) on the river. The effluents have significantly reduced since the Clean Water Act of 1972.

“…we could see, month to month that the river was getting better.”

In 1995, the EPA gave the Charles River its first report card. It said ‘D’. It corresponded to a river that does not meet standards for any swimming. In 2013, after more than 50 years (public swimming was banned in the 1950s), the Charles River Conservancy hosted the first recreational swim in the Charles. The same year, the EPA gave the Charles River an ‘A-‘. So what happened in the last 20 years? 

“When I arrived in 1990, the Charles was still dirty. So we wrote a proposal on studying the whole river and pretended that we didn’t know anything, because the bottom line is, we probably didn’t know anything. The first organization that funded us–we got 80 grand–was Enron!” said Bob. His initial efforts were focused on finding a way to effectively control combined sewage outflows. A significant improvement in the water quality came with increased attention towards the reduction and/or elimination of the CSOs. Over the years, the MWRA, with the help of the EPA, state government, and the CRWA has spent millions of dollars on projects to optimize CSO treatment and reduce or even eliminate CSOs in some places. The efforts have led to a decrease in CSO by 99.5% of its peak in the early 90s at 1.7 billion gallons a year.

The CRWA is lauded for its science-based advocacy that started to become the focus during Bob’s time at the CRWA. “I never got off the science machine. We put flow meters in the sewers to find out where the water came from in the first place. Everybody had just been calculating how much water came out of the pipe. Nobody figured out how it got there. In Watertown, a sewer pipe had collapsed and 100% of Watertown’s sewage was directly pouring into the river. It made it look like the whole river was filthy.” 

Bob continued, “We were physically monitoring the river. And we could see, month to month that the river was getting better. All of a sudden, all of the guys in the town started to get enthusiastic.”

The CRWA continues to physically monitor the river every month (Figure 3). The science behind the measurements is very important for organizations like the CRWA and the EPA to make continued progress towards cleaning rivers like the Charles. The following are some of the monitoring techniques currently used by the CRWA, EPA, and MWRA:

Figure 3: Pollution Monitoring in the Charles. Organizations like the CRWA enlist volunteers to conduct regular monitoring at numerous points along the river.

“There is no elevator pitch. ‘Do this and it will work’.”

Figure 4: Charles Lower Basin. Satellite view of the Charles lower basin, including neighboring cities of Boston, Cambridge and Watertown, where the river pollution is the highest.

For Pallavi Mande, Director of the Blue Cities Initiative at the CRWA, the work isn’t done.

“There is no elevator pitch. ‘Do this and it will work’,” says Pallavi. The Blue Cities Initiative incorporates the design of natural green corridors and infrastructure to help treat stormwater runoff before it enters the river – one of the last major sources of pollution in the Charles.

During my chat with Pallavi, I realized how complicated the challenge of cleaning the Charles River is, especially with severe implications of climate change are on the horizon. Beyond organizations like the EPA, CRWA and the MWRA, the town and city municipalities–which have different goals and resources–have to be part of future efforts. The cities and towns along the river’s lower basin are key stakeholders in the health of the river (Figure 4). Though the city of Boston has done the most projects that have impacted the river, it hasn’t always been proactive in dealing with the issues. Cambridge–being a smaller city–has been different in reflecting the awareness of its citizenry. Watertown and Waltham have been historically constrained for resources. The Charles River Climate Compact is a project by the CRWA to bring together watershed communities to work on climate adaptation strategies. 

“The Charles River Climate Compact was set up for such shared learning. Getting all these stakeholders to the same table has not always been easy. One of the biggest challenges we are facing currently is to balance how we communicate the more technical and useful concepts that are complex. Science is intrinsic to everything that we do. All our programs at the CRWA rest on making informed decisions based on the data collected,” said Pallavi about the challenges she faces in her job.

Despite the challenges, as the Charles has gotten cleaner, the continued efforts have gained momentum. Pallavi and the CRWA have now trained their sights on maximizing the impact of their efforts, especially to create value for the most vulnerable communities.“We are learning from everything we did right and (now) do it better.  And that can help inform the other stakeholders. Other watershed organizations are leapfrogging us by building on the work we have done. Mystic River Watershed Association is one such success story,” Pallavi says.

Figure 5: View of the Charles.

“That’s where you’ll find me

Along with lovers, muggers, and thieves”

The Standells croon into my headphones. I am placed comfortably on the lawn near the Harvard bridge by the banks of the Charles. As I finish wrapping up, I see something entirely different today.

Boston and Bostonians have embraced the song. Etched into memory and permanence. That might not change. But the Charles, the Charles has changed.

Vivek Hv is a recent graduate of the Master in Design Engineering program at the Harvard School of Engineering and Applied Sciences and Graduate School of Design

Cover Image: “Charles” by madprime is licensed under CC BY-SA 2.0

For More Information:

  • Follow the Charles River Watershed Association’s efforts at
  • Understand more about chlorine disinfection from the EPA here
  • To learn about different sources of pollution in the Charles, check out this article or this one from the EPA
  • Reada bout the US Army Corps of Engineers protecting the upstream Charles River Wetlands here
  • Find the Charles River report cards at this EPA site
  • Here is a list of infrastructure projects (including their costs and timelines) aimed at reducing CSOs


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