Charles River:

History & Issues Plaguing Its Water Quality

by Dave Brown, August 22, 2005


Located in eastern Massachusetts, the Charles River is a small American waterway compared to rivers like the Mississippi and Hudson.  However, when considering its role in allowing for urbanization to define the greater Boston area and inviting concentrated human impact to fiddle with the environmental stability of the Charles River area, this river is just as significant as the major rivers that have come to shape America’s history.  Max Hall, a journalist who won multiple awards for his 1984 article “The People’s River” featured in Harvard Magazine, expresses relevant reasoning as to why the Charles stands out among all rivers in the world.  “It may be the best example anywhere of an urban river that has been radically reshaped and controlled in the service of the public [1].”  In the following overview of the Charles River, you will better understand the publicly generated sources and effects of the water quality issues that have plagued the river, and the reasons for recent and ongoing research to improve the water quality.

A Profile of the Charles: Physical Characteristics

The Charles River, although relatively small, is the longest river entirely within Massachusetts.  According to agencies associated with the Charles River such as the Charles River Watershed Association (CRWA) and Environmental Protection Agency (EPA), the river weaves along an eighty mile winding path and a 350-foot drop in elevation from Echo Lake in Hopkinton to Boston, and is the heart of the surrounding 308-square-mile watershed (the area that drains water runoff into a specific river or other body of water).  It is fed by approximately eighty brooks and streams and passes through fifty-eight cities and towns before emptying into Boston Harbor.

Figure 1 - Map of Charles River [2]

            The Charles River crawls at an average of about 368-cubic-feet per second, a very slow rate compared to the Connecticut River, boasting a flow of about 16,180-cubic-feet per second [1].  The Charles River Watershed Association observes that due to its sluggish flow, the river water is brownish green in color because it “literally steeps like tea through the abundant wetlands along its path [3].”

Striped bass are just one amongst the twenty species of fish that can be found traversing the waters of the Charles River.  Herrings are another member of the river’s population and being that they are a migratory species, they require fish ladders installed along dams in order to swim upriver to lay their eggs [4]. Many public recreational activities occur along and within the Charles.  Although urban bustle affects the swimmability of the Charles around Boston, people can bathe in areas upstream from Watertown throughout much of the year.  Kayaks, motor boats, and yachts can be seen dotting the river along with a scattering of recreational parks.  The “Head of the Charles Regatta” is a very prestigious event bringing crew teams from all parts of the country to compete in a three-mile course that ends a half mile above the Eliot Bridge.  With such high utilization of the Charles River, it is important to develop and maintain a healthy environment for humans and water life alike.  We can look at the development of the Charles throughout its known history to understand where the issue of its poor water quality is rooted. 

A Brief History of the Charles

Let’s go back 11,000 years when glacial activity initially carved the shape of the Charles.  Its erratic bed was caused by glacial debris, the shape of the bedrock it cut through, and the remaining bergs of ice it had to navigate around.  Sea level at that time was seventy feet lower until it stabilized at its current location about 3,000 years ago.  Archeological evidence shows proof of human existence in the eastern Massachusetts area shortly after glacial retreat.  The region’s early beings utilized the river for transportation and fishing.  Fishing techniques like fish weirs (barriers of stakes, stones and clay) were built in the Charles, causing fish to collect in certain areas thereby making them easier to catch.  Other than using the waterway for fishing and transportation, these early individuals didn’t alter the Charles in any significant way.  The Viking explorer Leif Ericson might have passed along the coast around 1,000 AD, but to date, there is no evidence of Vikings settling in or near the area at that time [1].

Upon European exploration in the early 16th century and settlement of the area in the early 17th century, Native American life and its impact on the Charles River continued in this way.  The Algonquin speaking natives inhabited the area at that time, perhaps calling the river Quinobequin (meandering) or Shawmut, meaning “where there is a big river.”  When the English began to settle in what was then the Boston/Cambridge area, the river was named after Prince Charles who soon became King Charles I [1]. 

Figure 2:  The geography of the mouth of the Charles and the surrounding area from the 17th century [1]

During the 1600s and 1700s, transportation across the river via ferries and then bridges made settling along this area very easy.  In 1786, the famous Charles River Bridge was built following the ferry route that started in 1631, connecting Boston and Charlestown.  Known as the greatest American bridge at that time, this initial engineering of the 1503-foot Charles River Bridge sparked the construction of several other bridges that could now span such a broad width and benefit from financial success of bringing products and people to and from the Boston markets [1].  Throughout the 19th century, the city was expanded by filling in areas of water around the Back Bay and Charles River mouth.  Fill was taken from the three hills that made up Boston (Fort Hill, Copps Hill, and Trimont), and piled in the surrounding water [5].  This changed the shape of Boston’s and Cambridge’s lands and further affected the flow of the river, lending to its ability to clean itself. 

The most influential activity in altering the water quality of the Charles during the 19th century came as a result of industrialization and construction of dozens of mills along the river.  Because dams provided a major power source for the mills, many of these manmade barriers were constructed along the Charles, backing up the flow and sometimes causing flooding of pastureland and hay cutting areas as well as cutting off access by migratory fish to their spawning grounds upstream [3].  In 1820, a mill dam was laid across Back Bay and by 1880, the Back Bay was filled.  The addition of this dam and others along the river coupled with the shrinking of the Charles at its mouth slowed the rivers pace, causing a drastic change of tide.  The smell during low tide was repugnant, and became even worse due to pollution from industry and a boom in population around the area [1]. 

The pollution came as a result of various forms of dumping in the River from both industrial and residential development. These included byproducts from the mills as well as road run-off and residential waste.  Such contamination affected the surrounding wildlife, especially the fish populations which virtually vanished [3].   According to a CRWA document, “In 1875 a government report listed 43 mills along the 9.5-mile tidal estuary from Watertown Dam to Boston Harbor.  The Charles River was so polluted from industrial and domestic wastes including the raw sewage from almost all of Cambridge,  that the report recommended abandoning cleanup efforts on the river from south Natick (its midpoint) to the ocean, and focusing instead on the upper half, the Boston area [3].”

First Steps in Restoring the Health of the Charles

During the 1700s and 1800s, the legal concept of property ownership in America changed from private undisturbed ownership to productive use, economic development, and the needs of the community.  In the early 1900s, there was a public and political crusade for the Charles River to be exploited in order to contribute to Boston’s health, recreation and economic appeal.  Several men are attributed with their contributions to this effort including Charles Eliot, James Jackson Storrow, and John Ripley Freeman [1].

Charles Eliot, the son of Harvard’s President Charles William Eliot, was one of the pioneers in this endeavor.  He had joined the prestigious Olmsted landscape architecture firm that was responsible for the development and construction of New York City’s Central Park.    Eliot and others helped Massachusetts create the Metropolitan Park Commission in 1892.  They united with the Metropolitan Sewage Commission and the Metropolitan Water Commission in 1919 to form the Metropolitan District Commission with jurisdiction over the lower half of the Charles River, to serve the areas parks, water and sewage [1].

The Commission convinced political leaders to move the industrial area away from the base of the Charles River and to build a dam at the mouth of the River to keep out tides.  Additionally, they requested that the odoriferous estuary be turned into a man-made basin.  The product of their orders became known as the Charles River Basin and is similar to Norumbega Park, another man-made basin along the Charles River serving as a recreational center and created by mill dams in the late 1800s.

James J. Storrow was highly influential in persuading the Massachusetts legislature to investigate the need for a dam.  John R. Freeman was appointed the chief engineer.  Freeman was an MIT graduate who conducted the research and his thorough report in 1903 led the way for the construction of the dam [1].

These significant improvements to the basin and its management in the early part of the 20th century set a solid foundation for urban development.  At the turn of the century, metropolitan trunk sewers were built that intercepted aforementioned sewage before it became runoff into the Charles [1].  In the 1930s the Quabbin-to-Boston water supply system was built, fostering increased growth in Boston that would not have been possible with the previous local water supply system [3].  Although industrial pollution began to subside as a result of changed industry around the Charles, the metropolitan and municipal sewage systems’ inability to handle the cities population growth took over as the main proponent of pollution to the Charles [1]. 

 Combined Sewage Overflow (CSO) facilities and piping systems were built to act as an overflow storage/minor treatment facility for excess storm water and sewer flow.  During dry conditions, sewage water can easily flow to a treatment plant, but during rain storms, the capacity of the pipes can not handle the excess storm water flow, so overflow facilities accommodate this surplus of water.  Without CSO’s, this mix would back up into homes, businesses, and public streets.  Instead, these combined systems can store some of the mix and discharge the rest into rivers, lakes or coastal areas, subjecting them to higher pollutant loads [6]. 

Eventually this new system could not handle the wastes generated by the surge in population.  The Charles River then felt the impact of domestic, municipal and industrial wastes.  This pollution and the slowing of the river flow further prevented the Charles from being able to cleanse itself.  By the mid 1960s, the River was so polluted resulting in fish kills, trash, and almost unusable recreation areas due to the health risks and unpleasant smell [3].

Since that time, several steps have been taken in reducing the amount of pollutants that discharge into the River and Boston Harbor, including primary and secondary treatment plants, and outfall tunnel that discharges sewage into the deep waters of the harbor making it easier for the sewage to be diluted and swept away by the current.  In order to improve the water quality by treating waste water and reducing pollutants in such an aforementioned manner, it is important to discuss the major contaminants within the Charles and how they affect the water quality of the river.

Pollutants and Water Quality of the Charles River: Then and Now

       There is not too much recorded data representing the water quality along the Charles River previous to the latter half of the 20th century, but the effects from the industrial era on the water from the Charles was a result of byproducts from the mills built along the rivers for logging, the forging of iron, and processing wool [7]. 

Since then the sources of pollution have changed from industrial wastes, to contaminants from surface runoff from the combined sewage overflow system.  In addition to the human waste and other proponents of sewage being released into the Charles, Kathy Baskin, project manager for the CRWA explains that, “careless dumping of used oil, antifreeze, lawn mower gasoline and household or garden chemicals is a real threat to the health of the Charles River [8]."  Wherever these chemicals are not disposed of properly in the Charles River Watershed, they are washed into the waste water piping system, and will eventually be discharged into the River. 

            The major parameters currently affecting the Charles’s health include bacteria, chlorophyll a, phosphorous, and nitrogen compounds [9].  The presence and concentration of these elements are tested frequently at many sites along the Charles River and its tributaries to monitor the River’s water quality.

The presence of bacteria is the most critical evaluation of water quality in the Charles.  High levels of bacteria, namely E. coli, are found in the waste water from combined sewage overflows that discharge into the Charles River.  The National Center for Infectious Diseases lists E. coli as a recreational water illness (RWI), which is an illness spread by “swallowing, breathing, or having contact with contaminated water [10].”  E. coli is a compilation of hundreds of strands of bacteria found in the digestive tracts of healthy humans and animals, and some strands can be very toxic to human, wildlife, and aquatic health when coming in contact with contaminated water.  Bacteria laced water in the Charles can result in bloody diarrhea and occasional severe blood problems and kidney failure [11].  Although E. coli may not be a direct threat to human health, it shows the presence of sewage, which most likely contains a variety of other harmful bacteria and viruses [12].

The EPA has developed state standards for minimum concentrations of each health risk parameter that water bodies in Massachusetts must meet in order to have safe swimming or boating conditions.  In the latest CRWA water quality report, it is noted that the state standard for swimmable water is 126 colonies per 100 milliliters of water, and the boating standard is 630 colonies per 100 milliliters of water [9].  In this report, the CRWA notes that in 2004, “66% of 218 total E. coli samples fell below the state swimming standard, and 99% fell below the boating standard [9].”  In dry weather, with no CSO discharge into the river, the safe standards were met more frequently, while during storms, E. coli presence was much higher.  Over the past 10 years however, results have shown that the bacteria concentration has generally decreased even though it is still of major concern [13].

Chlorophyll a, phosphorous, and nitrogen all affect the water quality in a similar way.  Phosphorous comes from lawn fertilizers and “detergent rich wastewaters”, and nitrogen in the form of ammonia is found in untreated sewage [9].  In the appropriate chemical form, these nutrients are used by aquatic plants, promoting rapid algal growth.  The presence of chlorophyll a in the water indicates high concentrations of algae.  The plethora of plant life in the Charles River seems like it would be beneficial to the environment and water quality; however, the higher concentration of algae uses up a lot of dissolved oxygen found in the river bottom compromising survival of other aquatic species.  A Kentucky-based website on water quality explains the following about dissolved oxygen:

“Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from "gas bubble disease"; however, this is a very rare occurrence. The bubbles block the flow of blood through blood vessels causing death. External bubbles (emphysema) can also occur and be seen on fins, on skin and on other tissue. Aquatic invertebrates are also affected by gas bubble disease but at levels higher than those lethal to fish.  Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills [11].”

In the 2004 Monthly Monitoring Report prepared by the CRWA, 88% of 33 total phosphorous samples exceeded EPA limits of 0.024 mg/L and 50% of 30 orthophosphate met the same standards.  Out of 29 samples of nitrogen based ammonia, only 1 sample exceeded the EPA limits of 0.3 mg/L.  Furthermore, 78% of 28 samples of nitrate-nitrite exceeded safe levels of 0.57 mg/L, and 90% of 30 nitrogen samples exceeded the same EPA standards.  In regards to chlorophyll a, 64% of 31 samples failed to meet EPA limits of 0.00375 mg/L [9].

Besides these major components contributing to the water quality of the Charles, other physical and chemical conditions are measured.  According to the 2005 EPA Water Quality Report, the “Core Monitoring” program measures the following factors in addition to the bacteria and nutrients listed above: temperature, pH, specific conductance, turbidity, clarity, transmissivity, total organic carbon, total suspended solids, apparent and true color, and dissolved metals [13].  

Temperature changes and the change of pH of the water due to rain and runoff from urban activity affect the survival of aquatic ecosystems.  High temperatures decrease the amount of available oxygen in the water, and pH levels outside a particular range prohibit aquatic survival and can cause injury to human skin [11].  Specific conductance measures how well water can conduct an electrical current, which indirectly measures presence of elements that affect the electrical current.  Presence of these elements alters the conductance, and indicates a trace of contaminants from various sources of runoff, affecting the quality of the water [14].  Turbitity, clarity, transmissivity, apparent, and true color are more or less irrelevant measures of the water clarity, but can indicate changes in the make-up of the water. 

Government and Private Initiatives to Clean up the Charles

As you may already be aware, many organizations have taken responsibility in tackling the water quality situation of the Charles River.  The historical effects on the Charles, along with the continuing urbanization of this area, was instrumental in getting Federal, State, local and private agencies to step in and develop collective plans to remediate the water quality of the Charles River.

The Charles River Watershed Association (CRWA) was formed in 1965 in response to increasing public concern about the environment and the declining condition of the Charles River. Since its earliest days of advocacy, CRWA has figured prominently in major cleanup and watershed protection efforts, working with other citizen groups as well as local, state, and federal officials.  This association’s current work ranges from addressing faulty government water regulations to water quality monitoring of some thirty-seven sites along the eighty mile stretch of the Charles.  The Charles River Flagging Program displays the suitability of boating along the Charles.  Among other practices, the CRWA also employs a Total Maximum Daily Load project to quantify the pollutant loads impacting the Upper Charles River. The CRWA works collectively with organizations like the Environmental Protection Agency and Massachusetts Department of Environmental Protection [15].

The EPA was established in 1970 to set federal to local standards to protect human health and the environment in the U.S.  In 1995, the EPA established the Clean Charles 2005 Initiative, creating a taskforce and numerous subcommittees to restore the Charles River to a swimmable, boater-friendly, and fishable condition by Earth Day in the year 2005. The Initiative’s strategy was developed to provide a comprehensive approach for improving water quality through CSO controls, removal of illicit sanitary connections, storm water management planning and implementation, public outreach, education, monitoring, enforcement, technical assistance, and scientific studies.  The EPA reports significant and demonstrable progress in the improvement of the Charles River’s overall health and water quality since the birth of the Initiative. For example, based on data collected by the Charles River Watershed Association, the number of days when water quality is meeting state bacterial standards has increased from nineteen percent for swimming and thirty-nine percent for boating a decade ago, to fifty-four percent and ninety-six percent respectively, today. EPA data indicates that the swimming standard in the most heavily used part of the river, i.e. in the basin between the Massachusetts Avenue Bridge and the Longfellow Bridge, was met consistently during summer sampling events in 2004 [16].

Other organizations contributing to the clean-up of the Charles include the Army Corp of Engineers which conducts studies and implements programs benefiting the Charles River area, the United States Geological Survey which conducts various studies on the Charles River Basin, the Massachusetts Water Resources Authority (MWRA), the Charles River Conservancy, the Clean Charles Coalition, and many other organizations, towns, and local colleges.

Following the Path to the Clean Charles River

As you can see, water quality remediation has been a priority pertaining to the Charles River for almost a century and the efforts are still strong and widespread, giving optimism to those aware of the struggle to clean this river.  You too can become involved in the efforts through OUR Charles.  For more information about OUR Charles and information related to the Charles River and Water Quality, navigate around this website and check out the links page as well as the references below.



   [1]  Max Hall, The Charles: The People’s River.  (Boston: David R. Godine Inc., 1986).

   [2]  Charles River Watershed Association (CRWA), “Watershed Map and Towns,” http://www.crwa.org/index.html?wavestop.html&0 (August 2005).

[3]  CRWA, “History of the Charles River,”

http://www.crwa.org/index.html?wavestop.html&0 (August 2005).


[4]  CRWA, “Charles River Watershed Facts,”

http://www.crwa.org/index.html?wavestop.html&0 (August 2005).


[5]  “The History of Landfill in Boston,”

http://www.iboston.org/rg/backbayImap.htm  (August 2005).


[6]  Massachusetts Department of Environmental Protection, “The History of Landfill in Boston,” http://www.mass.gov/dep/brp/csos/csofaqs.htm  (August 2005).


[7]  Search Boston, “Boston History: The History of Boston, Massachusetts,”

         http://www.searchboston.com/history.html (August 2005).


[8]  CRWA, “Stenciling Project Warns Against Dumping in Storm Drains,”

         http://www.crwa.org/index.html?wavestop.html&0 (August 2005).


[9]  “CRWA Monthly Monitoring Program: Final Report,” (May 2005).


[10]  National Center for Infectious Diseases, “When You Swim, Swim Healthy!,”

         http://www.cdc.gov/healthyswimming/ (August 2005).         


[11]  “Important Water Quality Measurements,”             

         http://www.state.ky.us/nrepc/water/wcparint.htm (August 2005).


[12]  EPA, “Warning Issues on Bacteria Levels in Charles River in Milford, MA,”

http://www.epa.gov/region01/pr/1996/pr0912a.html (August 2005).


[13]  EPA, “Clean Charles 2005 Water Quality Report,”              


        (August  2005).

   [14]  “General Information on Specific Conductance,"

          http://bcn.boulder.co.us/basin/data/COBWQ/info/SC.html  (August 2005). 

   [15]  CRWA, “CRWA’s Mission,”                                                                                      

          http://www.crwa.org/index.html?wavestop.html&0 (August 2005).

[16]  EPA, “Charles River,”

       http://www.epa.gov/region01/charles/index.html (August 2005).