Sunday, April 24, 2011

Time and Tide in Cambridge

     Picture Cambridge in 1637, or 1700, or 1776. What do you imagine? Perhaps churches, small houses, or the common. Now imagine looking to the east. What you should see in your mind's eye is a stretch of salty, tidal marshland, and then open water for over a mile before you see the town of Boston in the distance. The Charles River as it flows through Cambridge today did not begin to take shape until the early nineteenth century, and it did not take the form it has today until the twentieth. Both Cambridge and Boston underwent land fill projects in the nineteenth century, also called land reclamation, in which solid land is made from wetland or water. Boston's project was massive, doubling the size of the city, but Cambridge's land fill was also very significant, as changed our relationship to the Charles forever.

     The watery gap between Boston and Cambridge was two miles at its widest point before any human interventions, which is three times the current distance.1 Near the present-day site of MIT, there were once oyster beds so large that they posed navigational challenges for boats passing through the basin.2 Just like the harbor it flowed into, the water had a tide; the difference in water level between high and low tide averaged nine feet.3 At high tide, East Cambridge became an island. Surrounding the river itself were salty marshes. Tidal marshes are divided into a higher zone and a lower zone, and it is typical for the low zone to be underwater at high tide and exposed at low tide. The tidal marshes in Cambridge included mudflats, which are created naturally by the buildup of sediment deposited in an estuary or other body of water. Such marshes are typically covered in grasses and rushes that have evolved to fit this unique niche, and they are also the home of a number of animal species, especially shellfish and migratory birds, that are adapted to their conditions.4

    Human alterations to the Charles River and its environs started slowly and snowballed through the nineteenth century. Early Cambridge settlers sometimes harvested the slender grasses growing in the marshes to dry and feed to livestock as “salt hay.” Harvesting salt hay didn't have much of an effect on the land or the ecosystem.5 In the 1790's, as part of an entrepreneurial boom of speculation and development, developers drained marshes and filled them with gravel, dug canals, and built wharves in the area that was becoming Cambridgeport.6 Unfortunately, increased construction created problems on the Charles River. In order to constructors bridges over the wide spans of water between Cambridge, Boston, and Charlestown, builders had to create causeways, altering the water flow. Now, local sewage was collecting in the narrowed river basin, and when the intertidal zone was exposed at low tide, the mud flats had a potent stench. In the following decades, human waste was joined by industrial waste.7 People began to recognize the altered marshes as a sanitary hazard as early as the 1820's, regarding clean, fresh air as a matter of the general welfare of the public.8 Construction and land fill on the Boston side throughout the nineteenth century changed the water flow considerably, making the problems even worse.

      In Cambridge, appetites for land were also growing. A group of property owners, seeking to develop the area for luxury residences, of the Charles formed the Charles River Embankment Company in 1881. and set out to develop the area in several ways. They constructed the Harvard Bridge in 1891. Afterwards, they attempted to build a sea wall on the Cambridge shore, using a suction dredge. The river bottom on the Cambridge shore was too hard for the dredge, but another company used the dredge on the Boston side. It caused a huge stench and a controversy over that stench by pumping up sewage, but the project was completed. 9 The luxury residences never materialized. Once the land was finished, new railroads in the area made it much more inviting to new factories.10

      The made land certainly boosted both cities' economy, but the loss of the marshes had long-term consequences. Wetlands aid in water filtration, including filtering sewage and industrial waste.11 At low tide, when the mud flats were exposed, the smell was awful. It got worse and stronger as the river became polluted by industry.12 The tidal current of the river itself had grown swift and dangerous since all the water from what was once a bay was now channeled into a smaller space.13 In 1873, the state Board of Health reported that Massachusetts had “no territory of equal extent... in so foul and so dangerous a condition” as Miller's River, which was a part of the Charles River area. In the same report, the Board speculated that if an epidemic disease was ever introduced in the area, the river would cause the disease to spread horribly. In 1878, the Board reported that “large areas have been at once, and frequently, enveloped in an atmosphere of stench so strong as to arouse the sleeping.”14

    To solve these problems, Cambridge and other municipalities took title to the shores of the river in the 1880's and 1890's. They built seawalls and scraped the river bottom with dredges, pumping the mud being dredged up into the areas where land was being created.15 Also in the 1890s, marshes west of the Charles were drained to become Soldiers Field.16 By the early twentieth century, the Massachusetts Legislature had gotten involved, forming the Committee on Charles River Dam and later on the Charles River Basin Commission. This bodies undertook the final steps to make that open stretch of water into the river we know today.17 They created a temporary dam by 1908, using locks and sluices to let water in and out. The permanent dam, by Lechmere point, was finished in 1910, and stood until it was replaced by the current Charles River Dam in 1972. The 1910 dam meant that the Charles would no longer have tides, marshes, or mud flats. 18 The land that had once been mud flats was soon built on for use by MIT, which moved from Boston in 1916.

    Creating land to build on and to eliminate the sanitary problems also meant destroying the marshes. This may not have seemed like a loss at the time, but we now understand just how vital marshes are. As mentioned above, salt marshes are a unique habitat, and the plants and animals that make their homes there are unlikely to thrive anywhere else. One example of an ecological disruption is the American Shad, a large herring which used to spawn in the Charles. Shad disappeared from this area early in the 20th century, probably because of pollution and the construction of the 1908 dam. They were reintroduced in the 1980's.19

     One of the biggest environmental and human consequences of making land on the Charles was not revealed until the 1950's, when a few significant hurricanes struck New England. Instead of the absorbent marshland, the river was surrounded by asphalt.20 The city embarked on a difficult and expensive project to replace the 1910 dam. The new dam included sophisticated pumps to prevent future floods, and they were very successful. In 1984, the region faced serious floods, but Cambridge got off lightly: the city had to deal with flooding from the rain, but not from an overflowing river.21 More importantly, the concept of “natural valley storage” began to emerge around the 1970's. This is the idea that we should preserve wetlands because they store water and help to prevent floods, an idea that is now well-established in environmental science.22 In a 1994 study, the U.S. Army Corps of Engineers found that wetlands along the Charles that had been saved prevented flooding that could have caused $17 million in damage.24 Now that Cambridge has learned first-hand the good and the bad that comes of altering a wetland area, we can carefully consider the potential effects of any future project. Today, Massachusetts has strict regulations on how wetlands, including the kind surrounding the Charles River, can be altered.

Earth Day 2011 was this past Friday, April 22. Happy belated Earth Day!

1Haglund, Karl. Inventing the Charles River. (Cambridge: The MIT Press, 2003), xvi.
2Hall, Max. The Charles: the People's River. (Boston: David R. Godine, 1986), 24.
3Haglund 7.
5Haglund 8.
6 Seaburg, Alan. Cambridge on the Charles. (Cambridge: Anne Miniver Press, 2001), 23.
7Haglund 1.
8Haglund 35.
9Whitehill, Walter Muir. Boston: a Topographical History (Cambridge: Belknap Press, 1959), 182.
10Hall 38.
11“Fact Sheet on Functions and Values of Wetlands.” Environmental Projection Agency. September 2001.
12Hall 36.
13Hall 36.
14 Massachusetts Board of Health reports, 1873 and 1878. Quoted in Haglund, 110.
15Hall 38.
16Hall 64.
17Hall 47.
18Whitehill 188.
19Hall 86.
20Hall 68.
21Hall 72.
22Hall 74.
23“Fact Sheet on Functions and Values of Wetlands.” Environmental Projection Agency. September 2001.


  1. Love that dirty water! Only now it is very well managed, clean, and beautiful. Strolling along the charles is the favored pasttime of many residents, and it is a major civic area with places like the hatchshell. Anyone interested in the changes to the waters around Boston should take a look at and for a quick glance, look at the animated gif at for a visual overview of one of the largest engineering projects of the 19th century. Learn why it's called Back Bay, why there is a strange line not far from Faneuil Hall, why there is a Tremont street, and (to return to topic) why Cambridge was -not- always a suburb of Boston, and how that made the decision to found Harvard in Cambridge was such an interesting one.

  2. It's true, the water is both clean and beautiful today. My post only covered a tiny slice of the land fill history in the area, and there are many great resources out there about Boston's land fill projects -- those you linked to among them.