The Hidden Hydrology of Boston & South End

Perhaps the most important type of landscape alteration in the watershed was the filling of the extensive salt marshes and tidal flats of the estuary downstream of Watertown (fig. 2). This landmaking activity along the lower Charles River began in the mid1600s, and did not conclude until the 1950s (Seasholes, 2003). In the early 20th century, the estuary mouth was dammed, creating a freshwater basin in the lower 9.5 miles of the river. A system of parks and parkways was built along the banks of the impounded river (Haglund, 2003). In addition to the mainstem river, virtually all of the remaining water resources in the watershed have also been altered. Most of the river’s tributaries, for example, were culverted, or placed into tunnels, and many of the ponds and freshwater wetlands in the watershed were filled to facilitate urban development
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

"Although the history of landmaking in Boston’s tidelands has been documented in detail (Seasholes, 2003), the original character and extent of freshwater resources in the Boston region, and their subsequent history of alteration, remain to be fully described."
Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

The water resources of the lower Charles River watershed have not been previously described in their broad physical and human context. One reason for this lack of study has been previously mentioned—most of the watershed’s streams, though named and mapped by the first settlers (figs. 2, 3, and 4), were placed into culverts (fig. 5) and subsequently forgotten during the period of rapid urbanization in the 19th and early 20th centuries. Although largely hidden from view, these streams continue to convey surface runoff and groundwater discharge to the Charles River, and to provide important ecological and recreational benefits. Improved public understanding of the Charles River watershed and its tributaries can be considered a vital component of the larger river restoration effort.
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

SOUTH BAY RESEARCH NOTES & RESOURCES:

TECHNICAL:

SAFETY & REGULATORY:

Hidden Hydrology

Modern overlays and translations

1630 Shoreline overlaid on modern South End and Back Bay

1894

1967

Geology of the Boston Basin (2011/2012)

The shoreline of the Charles River estuary and the harbor at the time the Massachusetts Bay Company Puritans arrived in 1630 has never been precisely known. Early records offer only general descriptions and very small scale and poorly surveyed maps. Bonner's 1722 map of Boston (fig. 16) is the earliest large-scale map and shows the shoreline of the peninsula at that time accurately in most places. It is interesting to compare this map with one just prepared by the U.S. Geological Survey which shows the high-tide shoreline as it probably existed in the early centuries of this millenium and perhaps when the first settlers arrived (fig. 6). The principal basis for drawing this shoreline was the limits of organic harbor muds and salt-marsh deposits as revealed by records of more than 30,000 borings drilled for engineering purposes throughout the city and in excavations in and around the city. Where information was lacking, the shoreline was drawn on the basis of historic records and topographic interpretation. The extraordinary growth of Boston by means of landfill at the expense of tidelands is evident from figure 6, and by comparing this map with Bonner's map, the changes wrought during the first 92 years of European occupation are evident. The earliest fill must have been used to build a causeway over the marsh that separated the North End from Boston proper. The filled area must have been extended rapidly, because early land titles show that much of the original marshland separating the two islands had been granted and occupied in the first few decades of the city's history.

A causeway over the marsh on Boston Neck must also have been a very early enterprise. Although town records tell of occasional flooding of stretches of Boston Neck, the record is vague about the extent of the Neck affected or the precise locations of the flooding. Undoubtedly, these early fills had to be replenished from time to time as they settled into the compressible peats of the marsh or were topped and eroded by high storm tides. Bonner's map does not show the marshy slough that extended up Water Street and along Congress Street as far as Franklin Street (today's names), nor does it show the full extent of the marsh at the north side of Beacon Hill. Some early extension of the natural shore is indicated on Bonner's map in the area labeled Barton's Point and Copper Works. We do not know who was responsible for this filling or when it was done. Bonner's 1722 map shows other sections of shore that were altered during the first century of occupation. The shore between Boston Neck and Windmill Point (intersection of East Street and Atlantic Avenue today) had been built hundreds of feet seaward and smoothed to a gentle curve. So had the shore between Windmill Point and the South Battery at the foot of Fort Hill, as well as the shore between South Battery and Long Wharf (now mostly State Street) and the Town Dock (crowded in and much reduced in size by 1722). Beacon Hill, particularly the neglected north slope, may have been a source of the fill. Fox Hill, at the foot of the Common, was another possible source. In addition, indications are visible in some modern excavations in Boston that the very early landowners improved their property by judicious grading. Small swampy spots were filled and low knolls leveled by several feet. This is revealed by patches of original soil and surface oxidation or leaching, such as is characteristic of wet places that have been uncovered in recent excavation in central Boston

The great era of landfilling in the Boston area was the second half of the 19th century. During this time, the entire Back Bayi was filled, as was the northern half of South Boston, the area in Cambridge that fringes the Charles River and on which the Massachusetts Institute of Technology now stands, and the marshlands of East Boston that included several drumlin islands (Noddles Island, Camp Hill, Togg Island, etc.). The last great landfill in Boston was made for the construction of Logan Airport. Governors Island was leveled and used for fill, and a second and smaller island, Apple Island, also within the airport site, was destroyed. Most of the site was filled in the early 1940's by dredging glacial clays from the bottom of the harbor and by pumping this thick mud slurry into settling basins where it formed a thick clay platform.

Kaye, C. A., The Geology and Early History of the Boston Area of Massachusetts, A Bicentennial Approach, Geological, Survey Bulletin 1476 (1976).

1770s

1770s map overlaid by Kaye's bedrock and fault map

1836, Creek Dividing Boston from Roxbury

1850	The Neck, 1630-1775

1836

1850

1860

MassMapper map with Bedrock, 3m Contour, Hydraulic Connectivity, Gulf of Maine Bathymetry overlaid with drawing of ancient, buried river valleys.

1700s map overlaid with Kaye's geological and fault map (1980)

Roxbury, 1852

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Whether what constituted old Boston was at one time an island, or was becoming one by the wasting forces of the elements, is an interesting question for geologists. We know that for nearly a hundred and fifty years scarcely any change had taken place in the appearance of the N eek ; but the action of the town authorities seems to indicate a fear that its existence was seriously threatened. Within the recollection of persons now living the water has been known to stand up to the knees of horses in the season of full tides at some places in the road, on the N eek. The narrowest part was naturally the most exposed, as it was the most eligible also for fortifying. At some points along the beach there was a good depth of water, and Gibben's shipyard was located on the easterly side a short distance north of Dover Street as early as 1722, and as late as 1777. Other portions, on both sides of the N eek, were bordered by marshes, more or less extensive, covered at high tides. Wharves were built at intervals along the eastern shore, from: Beach to Dover Street. In front of these wharves dwellings and stores were erected, facing what is now Washington Street. Josiah Knapp's dwelling, formerly standing at the corner of Kneeland Street, was one of these, his wharf being so near the street that the passers-by complained that the bowsprits of his vessels unlading there obstructed the highway. In the spring the road upon the N eek was almost impassable, especially before the centre was paved, which was from necessity done at last, but with such large stones that the pavement was always avoided by vehicles as long as the old road was practicable. Measures began to be very early considered to protect the N eek from the violence of the sea. In 1708 the town granted a number of individuals all the tract included within Castle and a point a little north of Dover Street, conditioned upon the completion of a highway and erection of certain barriers to "secure and keep off the sea." A second grant was made nearly eighty years later for a like purpose, extending from the limits of the first grant to a point a little beyond the former estate of John D. Williams, Esq., where the Cathedral now stands. From this beginning dates the reclamation of that extensive area now covered in every direction with superb public edifices or private mansions. A dike was built on the exposed eastward side, crossing the marshes to the firm ground on the Roxbury shore, before the Revolution, which traversed both the British and American ,works on the Neck. This followed in general direction the extension of Harrison A venue. A sea-wall was built about the same time on the west side, for some distance south from the bridge at Dover Street, nearly as far as Waltham Street. In a word, the general appearance of the N eek eighty years ago, to a spectator placed at the Old Fortifications, was similar to J-1 the turnpikes crossing the Lynn marshes, and was desolate and forbidding in the extreme, especially to a nocturnal traveller. From the old fortifications, northwanlly, the highway was called Orange Street as early as 1708. Washington Street was named after the memorable visit of the General in 1789, and at first extended only from near Dover Street to Roxbury line; the name was not applied to the whole extent of the preseut thoroughfare until 1824, when Cornhill, Marlborough, Newbury, and Orange became one in name as well as in fact.
OLD LANDMARKS AND HISTORIC PERSONAGES 'OF BOSTON, CHAPTER XV. THE NECK AND THE FORTIFICATIONS.

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"A canal fifty feet in width, extending from the wharf at Lamb's Dam Creek nearly to Eustis Street, just east of the burying-ground, was built about the year 1795. Its enterprising projectors, among whom were Ralph Smith, Dr. Thomas Williams, and Aaron and Charles Davis, proposed by this means to save two and a half miles of land carriage from the centre of Boston, in their supplies of fuel, lumber, bark for tanning, flour, salt, etc., and in conveying to the shipping in the harbor and stores on the wharves, as well as exporting abroad, the salted provisions and country produce which constituted a large proportion of the trade and commerce of the town at that time. The line between Roxbury and Boston passed through the centre of this canal. Gen. Heath's manuscript journal, under date of March 9, 1796, notes the fact that a large topsail schooner that day came up into the basin of the new canal in" Lamb's Meadow."

When Northampton Street was built in 1832, the terminus of navigation was made where Morse & Co. now have their coal wharf. North of this street and east of Harrison A venue was a dike to keep out the sea ; all else was marsh fiats save where the channel afforded sufficient depth to float small vessels laden with merchandise to Roxbury. The canal, never a paying investment, long ago ceased to be of commercial importance, and is soon to be filled up by the city.

A little to the east, in the direction of the old magazine, ran a wide creek, in which the rite of baptism was frequently performed. At one of these ceremonies of unusual interest, the pressure of the spectators against a fence upon its border was so great that it gave way, and a number of sinners were immersed nolens volen; - a circumstance which greatly interfered with the solemnity of the occasion.

The old canal-house, where the lumber-yard of Wm. Curtis now is, was the storehouse of Aaron and Charles Davis, pork and beef dealers and slaughterers. This was at the head of the canal. Near the pier was a little beach or landing-place where fishermen disposed of their piscatory wares. Among them. was Capt. Samuel Trask, a soldier of the Revolution, yet remembered by those who as boys frequented the beach and enjoyed its boating and other privileges as only boys can. The captain, who late in life kept a fishing vessel here, built in 1812, near the head of the canal, a schooner of about seventy tons. This vessel, laden with provisions by Aaron and Charles Davis, on sailing out of the harbor fell an easy prey to the British fleet then cruising at its entrance."

Drake, Francis, The Town of Roxbury (1878).

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"This land south of the Charles River was within the original Indian and royal grants to Massachusetts-Bay and belonged to the towns of Boston and Watertown. In 1632, there were many additions to the settlement at New Town (Cambridge) ; and, two years later, Hooker and his followers requested permission from the General Court to move to the valley of the Connecticut, as there was not sufficient land in New Town for their cattle. The petition was refused, and Boston and Watertown offered lands in what is now Brighton, Brookline and Newton, with the proviso that if the New Town people were to forsake the lands, they were to revert to the original owners. Two years later, Hooker and his companions departed for New Haven, and the land at Muddy River reverted to Boston and the meadow land along the river, to Watertown. The land was used only for grazing purposes at that time and for some time later. It was sometimes called Boston Commons, because the inhabitants of Boston ranged their cattle and swine here, taking them into the town for the winter.

In 1634, Boston made the first allotments of land at Muddy River, but there was no settlement for several years. On January 8, 1638, eighty-six poor families, comprising three hundred and thirty-seven souls, were allowed four and five acres apiece ; and, at the same time, grants of three hundred acres apiece were made to thirty of the principal people of Boston. Among these early grantees were the Rev. John Cotton, Governor Leverett, and Robert Hull, son of the mint master, whose farm passed into the ownership of his more famous brother-in-law, Judge Samuel Sewall. The Judge's farm was in the upper part of the town on Charles River, and its western boundary was Smelt Brook, in consequence of which the farm was called Brookline. Sewall's Point projected into the river ; and in the same vicinity according to ancient maps were many swamps and morasses, one of which was called White Cedar Swamp. It is probable that this was the scene of Irving's story of The Devil and Tom Walker ', which was laid in the "inlet of Charles's Bay. "

Jenkins, S., The Old Boston Post Road; Newton, Brighton, Brookline, Roxbury (1913).

GROUNDWATER COUNTOURS

"The Charles River, one of the Nation’s most historically significant rivers, flows through the center of the Boston metropolitan region in eastern Massachusetts. The lower Charles River, downstream of the original head of tide in Watertown, was originally a productive estuary. The water quality of the lower Charles River and its tributaries has been a matter of public concern and debate for at least the last 135 years. The longest river flowing entirely within Massachusetts, the Charles River winds 83 miles from its source to its mouth at Boston Harbor. The lower Charles River (the portion of the river downstream of Watertown Dam) flows the last 9.5 miles of this distance through a broad lowland.

Bedrock of the lower Charles River watershed consists of a sequence of sedimentary and volcanic rocks that were deposited about 580 million years ago in a broad sedimentary basin much larger than the present topographic lowland underlying the river. Stream courses in the lower Charles River watershed are also determined, in part, by zones of weakness in the bedrock associated with major structural features. For example, the mainstem of the Charles River overlies an east-west trending bedrock trough (or syncline) in the underlying Cambridge slate. Stony Brook and Muddy River, the two largest tributaries to the lower Charles River, follow the eastern and western limbs, respectively, of a large north-south trending fracture (or fault) that cuts across the Roxbury conglomerate.

Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

"The largest of these is the Stony Brook fault, which Billings (1976a) considered a normal fault along which the west side has been downthrown 640 m. It appears to be part of an en echelon system extending from the Narragansett basin to north of the northern border fault."

"In the lowest lying areas of the watershed, near the mainstem Charles and Muddy Rivers, an extensive, fine-grained deposit known as the Boston blue clay was laid down under shallow-marine conditions as the ice sheet retreated from the region. The properties of this clay unit have been extensively studied in connection with various large construction projects in Boston (Ladd and others, 1999). The Boston blue clay is completely overlain by recent estuarine deposits (sand, silt, clay, and salt marsh peat) deposited over the past 10,000 years (Rosen and others, 1993). The sedimentary environment that produced these estuarine deposits was the same environment encountered by Native Americans when they first reached the area 4,000 to 6,000 years ago, and by the first European settlers nearly 400 years ago. The estuarine deposits, in turn, have been completely covered by artificial fill over the past several hundred years, as will be discussed further below. A large portion of the artificial fill and disturbed urban land area is underlain by a sequence of blue clay and estuarine deposits."

The Back Bay was once a 738-acre system of tidal flats, marshes, and creeks that extended west from the base of Beacon Hill to the conjoined mouths of Stony Brook and Muddy River.  The Charles River drains a 268-mi2 area upstream of the Watertown Dam, and has an estimated mean annual streamflow at the dam of about 400 cubic feet per second.  The lower Charles River was originally an estuary that extended over 9 miles inland from Boston Harbor to rapids at Watertown.

Stony Brook is the largest tributary to the lower Charles River, draining 8,393 acres (13.1 mi2) in the Roxbury, Jamaica Plain, Roslindale, Hyde Park, and West Roxbury sections of Boston, and a small section of Brookline The stream originates in the Stony Brook Reservation, a State forest in West Roxbury.  The brook flows southeast through an open channel for its first mile, and then flows northward to the Charles River through a 7.5-mi-long, horseshoe-shaped brick conduit. The stream valley follows a roughly north-south fault in the underlying Roxbury conglomerate. Streamflow in Stony Brook is highly variable, in contrast to the mainstem Charles River. Dry-weather streamflows average about 10 ft3/s, and peak flows during major rainstorms can reach 1,000 ft3/s. During large rainstorms, flows in the Stony Brook conduit typically exceed flows in the mainstem Charles River at Watertown.

Muddy River and the upstream reaches of Stony Brook are the only two streams in the lower watershed identified on maps that are widely available today, such as the U.S. Geological Survey Boston South topographic quadrangle map, or the Massachusetts Geographic Information System’s electronic hydrography coverages. Information about the remaining streams and their watersheds may be found on historic maps or the storm-drain atlases of the lower Charles River municipalities. These drain atlases typically retain the original names of major culverted streams.

Muddy River drains 4,005 acres (6.3 mi2), almost exclusively in Brookline. The river originates in Jamaica Pond, a kettle pond set in glacial outwash at the southeastern edge of the watershed. Muddy River was originally a low-gradient tidal creek over most of its length. For a portion of its course, the stream coincides with the Muddy River fault.  Dry-weather flows (typically about 3 to 5 ft3/s) and water levels in Muddy River are affected by dam operations at the mouth of the Charles River. As with Stony Brook, streamflow is flashy and highly responsive to rainfall. Faneuil Brook has the smallest watershed area, (1,151 acres or 1.8 mi2), and the steepest average slope (8.9 percent) of all four major watersheds contributing to the lower Charles River. The stream originates at Chandler Pond in the Brighton section of Boston (figs. 1 and 5). Altitudes in portions of the watershed south of the pond exceed 240 ft above sea level, making it one of the highest areas in the lower Charles River watershed.

In addition to the four major watersheds, numerous smaller streams drain directly to the lower Charles River through the storm drain networks of the five municipalities in the watershed. These smaller streams, and their associated watershed areas are even less known to the public than the four major watersheds. However, they affect the hydrologic functioning and water quality of the mainstem Charles River, and it is important, therefore, to document their locations, characteristics, and principal outlets."

N.L. Hatch, The bedrock geology of Massachusetts, Professional Paper 1366-E-J, U.S. Geological Survey (1991).

Biosquare Groundwater Contours (1991)

Suffolk County Jail Groundwater Contour (1988)

MBTA Groundwater Contour Map (2001)

MBTA Groundwater Contour Map (1998)

Pervious layers of sand up to 6 meters (20 feet) thick are present and served as the source of water for the early settlers. The continuity of such layers was demonstrated (Aldrich & Lambrechts, 1986) during extensive dewatering on Harrison Avenue that caused water in observation wells located 1.6 188 CIVIL ENGINEERING PRACTICE 2011 /2012 kilometers (1 mile) away to drop 9 meters (30 feet) and that caused piezometers across the Charles River to drop up to 0.6 meters (2 feet). The excavation for the Boston Common Garage ran into an unanticipated water problem when the expected deep till turned out to be thick gravel whose large groundwater flow necessitated costly dewatering and drainage installations and a delay: of many: months (Kaye, 1961 & 1976a)
BAROSH & WOODHOUSE, Geology of the Boston Basin, CIVIL ENGINEERING PRACTICE (2011/2012)

sTREAMsTAT (usgs)

Tidal Hydrology

"The normal tidal range in the harbor is about 1.5 meters (5 feet) above and below mean tide and tidal fluctuations of groundwater levels below the city are seen only around the older part of the city along marginal waterfront areas, as measured in observation wells and some construction sites."

"Variations and anomalies in the piezometric surface often are related to dewatering for construction projects or pumping from deep basements. However, leakage from or into storm sewers is another factor. The many subway tunnels and deep utilities conduits commonly form either barriers or drainage paths that interrupt or control normal groundwater flow and create local variations in its level that can cause serious problems."

Barosh & Woodhouse, A City Upon a Hill: Geology of the City of Boston & Surrounding Area, Geotechnical Factors in Boston, Civil Engineering Practice, Vol. 26-27 (2011/2012).

Central Artery - top of immersed tube tunnel box in Fort Point Channel protrudes above the mud line; armor rock was placed on top of the tunnel box, altering 2.1 acres of subtidal waters; Russia Wharf (EEA #12821) -- pilings for the transient dock, some dredging; UMass/Savin Hill Cove Dredging -- improvement dredging of an existing navigation channel in Savin Hill Cove adjacent to the University of Massachusetts-Boston in Dorchester Bay.
Final Supplemental Environmental Impact Statement and Final Environmental Impact Report (EOEA# 12958) for the Federal Deep Draft Navigation Improvement Project Boston Harbor, Massachusetts, U.S. Army Corps of Engineers & Massachusetts Port Authority (April 2013).

"Boston Harbor is approximately 44 square miles in area. It has salinity features controlled chiefly by tides and is a vertically mixed estuary having more affinities with embayments than estuaries and aquatic life that is marine rather than estuarine. Boston Harbor received wastes from 2.5 million people plus industrial wastes from the Boston metropolitan area. The average discharge of wastes from this area exceeds 400 cubic feet per second, and the dry-weather discharge of tributary streams is near 100 cubic feet per second."

UNITED STATES DEPARTMENT OF THE INTERIOR, FEDERAL WATER POLLUTION CONTROL ADMINISTRATION, BIOLOGICAL ASPECTS OF WATER QUALITY CHARLES RIVER AND BOSTON HARBOR, MASSACHUSETTS July-August 1967, (January 1968).

"The conflict of the stream from South Bay, through the Fore Point Channel, with the ebb passing down from the upper harbor, and winding round on the South Boston Flats, gives rise to that other striking peculiarity of the deposit, its pointed and projecting shape on the borders of this channel. The water is diverted from its direct course to the bay, running almost at right angles to it, and the channel is constantly getting longer and shallower by means of this accumulation. It will be seen by an inspection of the map, that there is a remarkable correspondence between the outline of the flats and of the shore, the protuberance of the Upper Middle answering to that of the headland of the heights. On the opposite side of the channel there is a similarity in outline between the flats and Governor's Island, especially in the spot making off from the south point. These flats immediately round Governor's Island have the twofold character of deposits such as, on alluvial shores, always attach to points and headlands, and of deposits resulting from the confluence of streams approaching each other from opposite directions. The growth of the banks on both sides of the channel is probably now less rapid than it has been on the external borders ; it will continue to diminish. And the reason of this diminution is pregnant with instruction; it is the gradual narrowing of the channel that lessens the accumulation, the water being made so much more rapid in its course by this contraction, that it carries its burden beyond this point to drop it in a more favorable place."

Charles H. Davis, A Scientific Account of the Inner Harbor of Boston, with a Synopsis of the General Principles to be observed in the Improvement of Tidal Harbors, April I, 1851, Memoirs of the American Academy of Arts and Sciences, New Series, Vol. 5, No. 1 (1853), pp. 93-110

Essex River inlet, Massachusetts (Figure 1), contains the major morphological components of tidal inlets (Figure 2). Tidal inlets are the focus of the most dynamic changes that occur along barrier island coasts, exhibiting a geomorphic form that results from their adjustment to the dynamic action of both tidal currents and waves. Fromthe early studies of Jarrett (1976) and O’Brien (1931, 1969), it is known that the size of an inlet is governed by its tidal prismand, to a lesser extent, by the volume of sand delivered to the inlet via longshore transport. The morphology of the sand shoal fronting the inlet (i.e. ebb tidal delta) is controlled by the relative magnitude of the wave vs. tidal energy (Galvin, 1971; Hubbard, Oertel, and Nummedal, 1979; Oertel, 1975). Bruun and Gerritsen (1959) and later Hayes (1979) and FitzGerald, Penland, and Nummedal (1984) showed that the configuration of the inlet shoreline and longterm erosional-depositional processes at inlets are a product of volume and pathway of sand entering a tidal inlet and how that sand bypasses the inlet. Bruun and Gerritsen (1959) were the first to show that sand moving along the shore bypasses the inlet by sandbar migration under the influence of waves or by tide- and wave-generated current transport of individual sand grains. On coasts with large littoral transport rates, there is a tendency for some, but not all, inlets to migrate downdrift because of the preferential infilling of the mouth of the inlet on the updrift side. Most manmade modifications to tidal inlets have a significant influence on the erosional/depositional patterns on adjacent beaches. For example, artificially deepening an inlet for the purpose of developing a harbor can change the sand bypassing nature of the inlet, depriving the downdrift coast of its supply of sand and thus leading to potential erosion. Because inlets connect the coastal ocean with the sheltered backbarrier environments, including potential harbor sites, engineers have long been engaged in efforts to stabilize tidal inlets by constructing jetties to prevent their migration. Accordingly, the U.S. Army Corps of Engineers, to whom the authors of this paper are most grateful, sponsored much of the original research on tidal inlets in the United States.

Hayes, M.O. and FitzGerald, D.M., 2013. Origin, Evolution, and Classification of Tidal Inlets. In: Kana, T.; Michel, J., and Voulgaris, G. (eds.), Proceedings, Symposium in Applied Coastal Geomorphology to Honor Miles O. Hayes, Journal of Coastal Research, Special Issue No. 69, 14–33. Coconut Creek (Florida), ISSN 0749-0208.

The tides in Massachusetts Bay are forced by the tides in the Gulf of Maine which are in turn driven by the tides of the North Atlantic. The tides in the North Atlantic are the ocean's response to the gravitational attraction of the sun and the moon. These tides have wavelengths of order 9,000 km and periods of about once-a-day (diurnal) and twice a day (semidiurnal). Since the wavelength is much greater than the water depth (4 to 6 km), the waves behave -s shallow water waves whose velocity is controlled by the water's depth. T1. free wave response in the North Atlantic basin appears as an edge wave rotating counterclockwise around an amphidromic point (a point of no ,--vation change) in the center of the North Atlantic. This is illustrated in cotidal charts of the North Atlantic for the main diurnal and semidiurnal tidal frequencies (Figure 2). Along the east coast of the United States, the tide appears as a wave propagating down the coast, passing the mouth of the Gulf of Maine. This sea surface elevation change over Browns and Georges Bank excites the tides in the Gulf of Maine and Bay of Fundy system. The Gulf of Maine system is in near resonance at about the semidiurnal frequency (Garrett, 1972 & 1974), which causes a larger than normal tidal range, especially in the Bay of Fundy. The analysis of bottom pressure records in the Gulf of Maine by the response method gives the response function of the Gulf of Maine to the tidal potential (the gravitational attraction of the sun and moon). (Note that this is different from the actual forcing which is a function of the response of the North Atlantic to the gravitational forcing). The response function of the Gulf of Maine to gravitational potential determined from a 400 day bottom pressure record from Jordan Basin in the Gulf of Maine (Irish, 1990). Shows a peak in the amplitude response about the N2 tidal frequency (1.895673 cpd), just below the principal lunar tidal frequency (M2 at 1.932274 cycles per day). The response function gives the relative importance of each tidal line relative to the gravitational forcing. The N2 and M2 are amplified about 2.3 and 2.1 (relative to an equilibrium tide). The principal solar tide (S2 at 2.0 cycles per day) at a higher frequency, farther above the resonance frequency than the M2, is only amplifiea by a factor of 1.0. The resonance amplifies the importance of the semidiurnal tides over the diurnal tides in the Gulf of Maine, and amplifies the importance of the monthly modulation (interaction of the M2 and N2 frequencies) over fortnightly modulation (the interaction of the M2 and S2 frequencies). This is clearly seen in the bottom pressure record from Stellwagen Bank (Figure 3). The monthly modulaiion in amplitude due to the beating of the N2 and M2 frequencies dominates over the fortnightly modulation due to the beating of the The Massachusetts and Cape Cod Bays system is part of the Gulf of Maine, although somewhat separated from it by Stellwagen Bank. The tides in the Gulf of Maine drive the tides in Massachusetts and Cape Cod Bays. The resonance of the Gulf of Maine system simplifies the tidal analysis as discussed below. During the Massachusetts Bays field program, the tidal elevation was measured by several bottom pressure instruments as well as coastal sea level at sites shown in Figure 1. The bottom pressure (Figure 3) and current records (Figure 4) taken on Stellwagen Bank were chosen as representative records of the
tide forcing (elevation and flow) of Massachusetts Bays and used for more detailed analyses. Figure 5 shows power density spectra for the pressure (sea level) and currents at this staltion. The semidiurnal tidal peaks dominate the variance of both sea level and current velocity.

Irish & Signell, Tides of Massachusetts and Cape Cod Bays, Woods Hole Oceanographic Institution, DTIC Technical Report

Circulation in Massachusetts Bay results from tidal forces, wind-induced motion, and other factors such as the Earth's rotational and atmospheric pressure variations. The circulation is generally counterclockwise, and winds are typically offshore from the west. Water depths in Boston Harbor outside the navigation channels range from 10 to 15 feet at mean low water. Depths of nearly 90 feet occur in the channel at President Roads. The mean tidal rise and fall of Boston Harbor is approximately 9.5 feet. Maximum currents have been noted at Hull Gut at 2.6 knots during ebb tide and in President Roads at 2 knots both during ebb and flood tides (Figure 8).
Boston Harbor and Massachusetts Bay: Issues, Resources, Status and Management Proceedings of a Seminar Held June 13, 1985 Washington, D.C.

Burried River Valleys

"When Boston was first settled in 1630, the peninsula was connected to the mainland by a narrow, rather tenuous low-lying isthmus of land called The Neck. It united the colonial city of peninsular Boston to the mainland at the town of Roxbury. Only 50 to 100 feet wide in places, it frequently flooded in storms and was threatened at high tide. As early as 1735, wooden "wharffes", and by 1790, stone wall dams were erected to hold back the sea. There was room for only one road across the Neck from Boston to the mainland at Roxbury. It went from from Cornhill Street to Marlborough to Newbury and finally Orange near the mainland. After the American Revolution, in honor of George, its names were unified into Washington Street with street names that cross it changing their names out of respect. It was the Commonwealth's longest street and continues through Roxbury to the Rhode Island state line. It's roughly paralleled by the tracks of the MBTA's Orange Line that inherited its name from Orange Street. As for the town of Roxbury, like so many others that surrounded Boston, it was annexed in the nineteenth century, 1868 for Roxbury. The "dissolved municipality" is one of 23 others (including Back Bay that was later "created") that are now official neighborhoods of Boston."
https://written-in-stone-seen-through-my-lens.blogspot.com/2017/02/urban-geology-part-i-filling-in-of.html

"On Oct 5, 1795 a Committee was appointed to Contract someone to open up the old Lamb's Dam Creek and land below the Town Wharf of Roxbury. ( Near Albany and Northampton traveling between Harrison and Davis (Albany st} extending almost to Eustis st). and then out to the Four Point Cannel. Again in 1796 an act for the Incorporation of the Canal was passed and on April 5 1796 a new Contract for digging was made. This lasted to Aug 1801 till it was found the work was not completed in the mannor agreed upon. One Patrick Welch was then contracted to finish the Canal through the flats out to the Four Point Channel at 5 dollars per sow load and 1 quart of West India Rum was allowed to the 5 dollars per load. Mr Welch worked the contract for a time till he considered it a bad deal. Another contract for 7 dollar was made with Seth Lawrence and after a few months he gave it up. Day laborers were employed by the Town of Roxbury by the day. This went on for over 6 years the work being done by the Town of Roxbury. The Canal proved to be a failure and on the 12th of June 1818 a Committee was appointed to deal with it. The next year the 4 of Oct 1819 the decision was made to fill the Canal to Lambs Dam (Northampton st), It was found in 1822 that the Canal was filled with a strip of land that belonged to Boston. The Arbitrators in 1882 awarded Boston land 250 feet by 250 feet. "all that part of the Canal lying west of the old boundry as it existed after it was filled. (From Harrison today, measure towards Albany 250 feet.) By the 1870s the Lambs Dam area called Chester Park, had become a receptacle of filth, with dark water sewage pipes connected to the Canal. The Canal was dredge in 1872 only to see the filth increase the next year. The lower part along Chester Park was shortly after filled."
(Roxbury Historical Society).

Several deep valleys eroded into bedrock and filled or nearly filled by unconsolidated deposits are known in eastern Massachusetts (Crosby, 1939) and the coastal areas of the New England States (Upson and Spencer, 1961). The valleys were formed by stream erosion prior to the last glaciation and have been somewhat modified by glacial processes (Upson and Spencer, 1961, p. 44). The unconsolidated sediments in the buried valleys were probably deposited mainly during and at the close of the last glaciation, although some of the more deeply buried sediments may have accumulated before the beginning of the last glaciation. The surf ace deposits are mostly swamps formed in part during late-glacial and postglacial time. In the Norwood quadrangle, a buried valley underlies the present surface valley of the Neponset River, and buried tributary valleys underlie Reservoir Pond and Ponkapog Brook, Purgatory Brook, and Wigwam Pond (pi. 2). In a few places, test borings and bedrock outcrops indicate the approximate position of the main buried valley, but nowhere is the information sufficient to determine its width or greatest depth. The evidence available indicates that there is an older valley floor, probably only a few tens of feet above present sea level, incised by a relatively deep narrow valley to a depth of more than 100 feet below present sea level. Although partly dissected, much of the older floor apparently is still preserved under a thin cover of glacial and postglacial deposits. Outcrops of bedrock south of Norwood Airport and elsewhere are the tops of small hills on this floor. The axis of the main channel of the buried Neponset River valley is inferred to enter the west side of the quadrangle near the present river channel (pi. 2) and to continue eastward under East Walpole to Neponset Street where it turns northeastward approximately beneath the present course of the river. Northeast of Route 128 the buried valley probably underlies the Neponset River for about a mile. Farther northeast its location is in doubt. Crosby (1939, p. 379) believed that it crossed the northwest corner of the Blue Hills quadrangle along the valley of Trout Brook. Low relief and sparseness of outcrops along the Neponset River in the extreme northeast corner of the quadrangle suggest this as another possible location for the buried channel, but the continuation of the buried channel to the northeast in the Newton and Boston South quadrangles is uncertain. The present wide surface valley terminates abruptly in the southcentral part of the quadrangle. From there westward the location of the buried valley is uncertain. Crosby (1939, p. 375) located it under East Walpole and along the south side of Bird Pond about as shown on plate 2. Seismic measurements by the U.S. Geological Survey about a mile south of East Walpole (pi. 2) showed unusually thick surficial deposits but did not locate the main part of the buried , valley in that area.

Only limited information is available concerning the buried tributary valleys. A deep well at the State Hospital School north of Reservoir Pond penetrated 238 feet of gravel, clay, and till before reaching bedrock about 43 feet below sea level (I. B. Crosby, oral commun.). Crosby (1939, p. 379) considered this depth to be evidence of an important tributary valley. The course of this tributary is uncertain, but it may trend northward and lie approximately beneath the present course of Ponkapog Brook. A second Neponset buried valley tributary apparently trends south from the vicinity of Interchange 56 and 57 on Route 128 to Purgatory Brook where it turns southeast beneath the present surface stream. Several wells drilled for Norwood a short distance east of Route 1 near
Purgatory Brook show that the bedrock is at least 50 feet below sea level in this area. Another buried tributary apparently trends north from the vicinity of Wigwam Pond towards the buried valley of the Charles River north of the quadrangle. Two wells in this valley drilled about 150 feet southeast of Route 1 and 2,000 feet south of the north edge of the quadrangle are reported to have ended on either boulders or bedrock a little above sea level. Although the Wigwam Pond and Purgatory Brook tributaries may connect in the vicinity of Route 128, bedrock exposures at Interchanges 56, 57, and 58 suggest that the tributaries are separated by a bedrock divide. In addition, borings 1500 feet apart at the railroad crossing and Interchange 58, reached bedrock at shallow depths. On the other hand, the apparent alinement of the valleys and the anomalous southward course of the Purgatory Brook buried valley for about 1 1/4 miles south of Route 128 may indicate a buried valley formed by a stream that flowed from the Charles River buried valley southward to the Neponset River buried valley.

Crosby's map (1939, p. 375) shows a buried tributary valley in Walpole which trends northeast from the southwest corner of the Norwood quadrangle near Washington Street. Topography and lack of outcrops indicate a buried valley here, but without more definite evidence it is not shown on the surficial geologic map (pi. 2). Glacial erosion of the buried valleys undoubtedly varied with their orientation. Where the glacier flowed parallel to the valleys, as in the Purgatory Brook tributary, it probably eroded most of the older sediments and gouged into the bedrock. Where the glacier moved at right angles to the valleys, it was less effective in removing the older sediments, and some may remain, especially on the lee side of prominent bedrock ridges such as those crossed by Neponset and Canton Streets.

Several deep borings in the Neponset River buried valley (see pi. 2 and table 1) have supplied information on the thickness of postglacial material, sand, gravel, and till. Little is known about the till in the Neponset River buried valley. It is recognized in driller's logs of boreholes by the large number of blows required for penetration and by boulders. Older sediments may underlie the till in some places, but in. other places the till probably rests directly on bedrock. The till is overlain by a deposit of sand and gravel (table 1) reported as yellow in some of the boreholes.

A thick deposit of fine gray sand that has some intermixed clay and fine gravel overlies the yellow sand and gravel deposit and constitutes the major volume of sediments in the parts of the buried valleys that underlie the Neponset River and Purgatory Brook marshes; however, this sand is not found elsewhere in the buried valleys. Its greatest thickness shown by the boreholes is about 120 feet, and its greatest known depth below sea level is about 88 feet. This sand is probably a late-glacial deposit formed in a lake that coincided in extent with the present Neponset River and Purgatory Brook marshes. The lake was about Q l/2 miles long and had an area of about 51/2 square miles. Its surface was not higher than about 50 feet above present sea level.

The estuarine deposits of clay, silt, sand, and peat in the Boston area were laid down during the last rise in sea level. These deposits (Upson and Spencer, 1961, fig. 4, p. 42) extend as much as 90 feet below sea level.

Although boreholes show that the fine sand in the Neponset buried valley extends to at least 88 feet below present sea level, it does
not appear to be an estuarine deposit connected with those in the Boston area. No channel low enough to allow sea water to enter the Neponset River valley is known north and northeast of the Norwood quadrangle. The fine sand deposit probably formed in an isolated lake that was dammed by glacial deposits. This lake was eventually filled and obliterated.

Geology of the "Norwood Quadrangle ' Norfolk and Suffolk, , Counties, Massachusetts, NEWTON E. CHUTE, GEOLOGY OF SELECTED QUADRANGLES IN MASSACHUSETTS, GEOLOGICAL SURVEY BULLETIN 1163-B, Prepared in cooperation with the Commonwealth of Massachusetts ^ Department of Public Works (1966).

Geology of the Boston Basin (2011/2012)

BURIED VALLEYS OF THE BOSTON AREA GENERAL FEATURES
The Boston area, for purposes of this report, is an area of about 400 square miles bordering Boston Harbor on the north and west. It is occupied by parts of the present-day Charles, Mystic, Maiden, and Neponset Rivers. In comparison with such rivers as the Connecticut or the Kennebec, these are insignificant streams; however, the bedrock valleys associated with them reach considerable depth. The bedrock valleys have been studied by geologists of three generations, and considerable data are available. The most comprehensive and the most recent works on the geology of the Boston area are those of Billings (1929) and La Forge (1932). As described in these reports, the Boston Basin is a structural depression, like the Narragansett Basin, and is underlain by complexly folded and faulted sedimentary and volcanic rocks which Billings (1929, p. 106) considered to be of Pennsylvanian (?) and Permian age. These rocks are separated by fault contacts from older igneous and metamorphic rocks that range in age from Precambrian to Devonian(?). In general, the younger rocks are less resistant to erosion than the older ones and, having been more extensively and deeply dissected, form a topographic as well as a structural depression. A major fault marks the north boundary of the basin. This fault
was named the Northern Border Fault by Billings (1929, p. 107, fig. 2), and was further described by La Forge (1932, p. 63). The parts of the valleys that are north of the fault are appreciably shallower than the parts to the south. Also, at places the valleys or their tributaries seem to have been localized along the fault zone itself. The unconsolidated sediments that rest on the bedrock are virtually all glacial deposits or marine and fluviatile deposits formed in association with glaciation. La Forge (1932, pi. 2, p. 79-86) mapped the glacial deposits of the Boston area in moderate detail, and Judson (1949) made a rather thorough study of the subsurface deposits as revealed by borings and foundation excavations for certain large buildings in Boston. For most areas discussed in this paper, the term "bedrock valley" is preferably used. In the Boston Basin area, however, the valleys are so extensively filled, or buried, that most of them have no surface expression. They are often referred to in the older literature as "buried," and the one beneath Fresh Pond has the word "buried" in its name. Therefore, the bedrock valleys of the Boston area are generally referred to in this part of the text as "buried valleys." (See p. M4.) Figure 6 shows the approximate outline of the buried valley system that probably underlies the Boston area and the locations of the sections given in plate 2 and figure 8. In subsequent paragraphs, localities referred to by number are shown on figure 6. Most of the buried valleys lie approximately as shown by I. B. Crosby (1937) although the courses are slightly different, as indicated by work done by Halberg and Pree (1950, fig. 3) and by data collected in the course of the present study. The thalweg of the Aberjona-Fresh Pond buried valley is from Chute (1959, pi. 14) but is modified slightly in part on the basis of test-well data furnished by H. N. Halberg (oral communication, 1959). Table 4 lists the localities for which sections are drawn and the source of the data for each. The names of most of the buried valleys used in this paper are the names of the present streams. Some explanation however, is desirable. W. O. Crosby (1899, p. 302) postulated that the ancestral Merrimack River (fig. 1) followed a valley southeastward from New
Hampshire to a position beneath the present Aberjona and Mystic Rivers (fig. 6) and thence to Boston Harbor. I. B. Crosby (1937) at first adopted this postulate but later evidently modified the view, as he wrote (1939, p. 374), "The valley coming from the north is in line with the projection of the buried valley of the Merrimack, and these valleys will be described as the pre-glacial Merrimack-Mystic Valley, although it is not yet proved that these were one continuous valley." La Forge (1932, p. 79) stated that there is no evidence that the Merrimack extended as far south as the Aberjona Eiver, a view supported by more recent seismic surveys (Lee and others, 1940) and investigations of ground-water conditions near Lowell, Mass. (J. A. Baker, oral communication). Thus the name "Merrimack" should not be used. Halberg and Free (1950, p. 209-210) showed that the main stem of the buried valley beneath the Aberjona River continues southward, passing beneath the Mystic Lakes, and instead of following the present Mystic River continues more nearly southward beneath Spy Pond and Fresh Pond. Thus, although I. B. Crosby used the name "Merrimack-Mystic," the use of "Mystic" is also incorrect. Halberg and Pree (1950, p. 209) used the term "buried Aberjona valley" informally, and also (1950, p. 211) the name "Aberjona- Fresh Pond buried valley." Subsequently, Chute (1959, p. 189) formally applied the named "Fresh Pond buried valley." Fresh Pond lies above the extreme southern part of the buried valley, and use of this name ignores the greater, or northern, part of it beneath the Aberjona Valley. Accordingly, in this report the writers use the name, "Aberjona-Fresh Pond buried valley" as it is more descriptive and has some precedence in former usage. For the most part, the Charles buried valley follows the course of the Charles River except in Boston proper where it lies several miles to the south. This valley, because of its possible upstream continuation in an ancestral Sudbury River (I. B. Crosby, 1937) is considered to be the major buried valley of the Boston area. Halberg and Pree (1950, p. 208-211) also briefly described the other valleys beneath the Maiden and Neponset Rivers. Only the one beneath the Maiden, herein called the "Maiden buried valley," is further described in this report.
Bedrock Valleys of the New England Coast as Related to Fluctuations of Sea Level By JOSEPH E. UPSON and CHARLES W. SPENCER SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 454-M

A million years ago the Merrimac did not turn eastward at Lowell and flow into the sea at Newburyport. but instead it continued south from Lowell, by Winchester, and through Cambridge and Boston as we have seen. It was a large river and flowed in a deep valley. The Charles joined the Merrimac at Allston, but it was a different Charles, without falls, and not so crooked as the present river. There was a river somewhat similar to the Neponset, but without the rapids at Mattapan and Milton Lower Mills. The Mystic did not exist at all, but the Merrimac flowed where the upper part of the Mystic now is. We see that, though the main features of the topog-raphy were like the modern ones, the rivers and ponds were entirely different. They find that under the Back Bay it is two hundred feet to solid rock. A buried valley can be traced eastward under the South End into the Old Harbor or Dorchester Bay.
Northward this buried valley extends under Cambridge and Winchester to Lowell. By studying these well records, we know what the country looked like before the present soil was deposited on the rocks.
Crosby, BOSTON THROUGH THE AGES THE GEOLOGICAL STORY OF GREATER BOSTON, MARSHALL JONES COMPANY

"A small tributary of the Charles River flowed northwest across Back Bay from the west end of Boston Neck and then northeastward to the ancestral Charles River (Judson, 1949). Other smaller channels which appear to radiate outward beneath the harbor, were probably early ones abandoned as the Charles River cut deeper... Kaye (1970) noted tributaries to the lower Charles Valley: northeast flowing ones, which apparently followed fault zones, across Dorchester Heights, and a southwest flowing one below Fort Point Channel. The buried valley of the Charles is joined by the buried Neponset Valley from the south and turns northward to join the buried Malden Valley and curve seaward off Deer Island. (Crosby, 1937; Halberg & Pree, 1950; Upson & Spencer, 1964).

These are deep channels and the full understanding of the ancient Charles River system is hampered by the lack of elevation control of the channel as it leaves the harbor... The lower Charles appears to have first flowed east toward South Station at an elevation of -27 meters (-90 feet) MSL and was likely joined by a tributary that passed beneath Beacon Hill (see Figure 3-70). The lower, eastern end was first diverted below elevation -30 meters (-100 feet) MSL by a stream from ·a lower level that worked its way upward above Fort Point Channel from Carson Beach."

Barosh & Woodhouse, A City Upon a Hill: Geology of the City of Boston & Surrounding Area, Geology of the Boston Basin, Civil Engineering Practice, Vol. 26-27 (2011/2012).

The longest river flowing entirely within Massachusetts, the Charles River winds 83 miles from its source to its mouth at Boston Harbor The lower Charles River (the portion of the river downstream of Watertown Dam) flows the last 9.5 miles of this distance through a broad lowland
Bedrock of the lower Charles River watershed consists of a sequence of sedimentary and volcanic rocks that were deposited about 580 million years ago in a broad sedimentary basin much larger than the present topographic lowland underlying the river. Some of the rock layers in this sequence consist of relatively soft siltstones and slates (known collectively as the Cambridge slate), which are easily eroded. Other rock formations in the sequence are more resistant to erosion. The most well-known of these formations is the Roxbury conglomerate (known locally as “puddingstone”), which consists of pebbles and cobbles in a sand matrix
Subsequent folding and fracturing of the region’s rock formations, and erosion of these rocks by water and ice over millions of years resulted in the present topography of the lower watershed
Stream courses in the lower Charles River watershed are also determined, in part, by zones of weakness in the bedrock associated with major structural features (Skehan, 1979; 2001). For example, the mainstem of the Charles River overlies an east-west trending bedrock trough (or syncline) in the underlying Cambridge slate. Stony Brook and Muddy River, the two largest tributaries to the lower Charles River, follow the eastern and western limbs, respectively, of a large north-south trending fracture (or fault) that cuts across the Roxbury conglomerate (Skehan, 1979; 2001; Goldsmith, 1991).
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

During the last million years, a series of glacial episodes left an unmistakable signature on the New England landscape. The most recent ice sheet retreated from the Boston area about 15,000 years ago (Rosen and others, 1993). It left two principal types of deposits in the lower Charles River watershed: (1) glacial till (a typically hard and compact mixture of clay, silt, sand, pebbles, cobbles and boulders deposited directly by glacial ice); and (2) stratified or layered deposits, which may include both predominantly coarse-grained sand and gravel (or outwash) deposited by meltwater streams, and fine-grained silt and clay deposited in the standing water of a lake or a marine water body. Upland areas of the watershed are generally overlain by till; and lowland areas, where not covered by artificial fill, typically have stratified deposits at the surface (fig. 8)
Outwash is common in many lowland areas of the watershed. Outwash plains typically contain depressions, known as kettles, caused by the melting of stagnant blocks of glacial ice after the retreat of an ice sheet. If the water table in the surrounding outwash plain is higher in altitude than the base of the kettle, it will generally become a ground-water-fed kettle pond
In the lowest lying areas of the watershed, near the mainstem Charles and Muddy Rivers, an extensive, fine-grained deposit known as the Boston blue clay was laid down under shallow-marine conditions as the ice sheet retreated from the region. The properties of this clay unit have been extensively studied in connection with various large construction projects in Boston (Ladd and others, 1999). The Boston blue clay is completely overlain by recent estuarine deposits (sand, silt, clay, and salt marsh peat) deposited over the past 10,000 years (Rosen and others, 1993). The sedimentary environment that produced these estuarine deposits was the same environment encountered by Native Americans when they first reached the area 4,000 to 6,000 years ago, and by the first European settlers nearly 400 years ago. The estuarine deposits, in turn, have been completely covered by artificial fill over the past several hundred years, as will be discussed further below. A large portion of the artificial fill and disturbed urban land area shown in figure 8 is underlain by a sequence of blue clay and estuarine deposits
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

The Charles River, one of the Nation’s most historically significant rivers, flows through the center of the Boston metropolitan region in eastern Massachusetts. The lower Charles River, downstream of the original head of tide in Watertown, was originally a productive estuary and important source of fish and shellfish for the Native Americans of the region
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

Boston Basin has less sedimentary and more igneous rocks, in down folded or downfaulted basins.
For most areas discussed in this paper, the term "bedrock valley" is preferably used. In the Boston Basin area, however, the valleys are so extensively filled, or buried, that most of them have no surface expression. They are often referred to in the older literature as "buried," and the one beneath Fresh Pond has the word "buried" in its name. Therefore, the bedrock valleys of the Boston area are generally referred to in this part of the text as "buried valleys." (See p. M4.)
For the most part, the Charles buried valley follows the course of the Charles River except in Boston proper where it lies several miles to the south. This valley, because of its possible upstream continuation in an ancestral Sudbury River (I. B. Crosby, 1937) is considered to be the major buried valley of the Boston area. The lower reaches of the thalwegs of the bedrock valleys of the Boston Basin area lie between 230 and -245 feet msl. The elevations at about -243 feet msl on the Charles Buried valley in Boston (pi. 2(7), at about -244 feet msl on the Charles at Columbus Park (pi. 2Z>), and at -230 feet msl at the lower end of the Maiden buried valley indicate a very low grade which may represent a local base level somewhat below - 240 msl, at say -250 feet msl.Bedrock Valleys of the New England Coast as Related to Fluctuations of Sea Level By JOSEPH E. UPSON and CHARLES W. SPENCER SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 454-M (1964)

The depth to water in the installed observation well ranged from 7.0 ft to 7.6 ft below the ground surface. In addition Boston Wharf Company has installed several observation wells in the area. These wells indicate that the water levels range from El. 5 to El. 9 (5 ft to 14 ft below ground surface) across the site. Groundwater levels may fluctuate due to variations in season and precipitation, leakage into or out of existing utilities and utility bedding materials, adjacent construction activities, and other environmental effects. As a results water levels encountered during construction may vary from those recorded in the observation well and borings during the observation period.
Fort Point Channel Combined Sewer Overflow Control Project, BWSC Contract No. 95-206-014 (2006)

Marshes, Wetlands, And Flooding

"The land area of Metropolitan Boston has a varied and uneven topography, typical of areas once covered by glaciers and of tidal estuaries. Near the harbor the three main waterways of the area are, or were, bordered by extensive flat marshy areas. At some distance from the harbor the land is rolling and the topography is characterized by hills, valleys, streams and lakes. The softer clays and silts predominate in the areas adjacent to the harbor and waterways, and sand and gravel in the areas farthest away from the harbor and tidal estuaries."

"There is a substantial amount of ground water in the subsoil throughout the area under investigation which tends to maintain the summer or dry-season flow in the upland waterways. This infiltration of ground water into sewers appears to be relatively large."

Report of the Special Commission Investigating Systems of Sewerage and Sewage Disposal in the North and South Metropolitan Sewerage Districts and the City of Boston, Commonwealth of Massachusetts House, (June 15 1939).

The Roxbury Canal was filled multiple times. The 1885 sewer report noted the wester portion of the Canal “had been recently filled by the city” but “an influx of tide-water along the loose walls of the canal and through the filling” was causing issues with sewer installations.
The Roxbury Canal has a formal entrance and a “boat chamber” at the corner of Swett Street. Boats can be lowered into the street from a 11 x 4 ft opening in the street. This area was previously the Creek and Canal and reports also noted the area was full of mud, structures required piles, and that there were reports of quicksand. (Main Drainage Works, 1885).

“the old Roxbury Canal” which had been recently filled by the city an influx of tide-water along the loose walls of the canal and through the filling occasioned some delay and expense . The water was finally kept out by double rows of tongued and grooved sheet piling.” A side entrance and boat chamber were built on this section, at the corner of Swett Street.” The latter structure resembled a very large manhole, with a rectangular opening from the street, 11x4 ft in dimensions.
1885 Main Drainage Works.pdf

"In a report to the Honorable City Council of December 17, 1874, they called the attention of that body to the conditions of the old Roxbury Canal, crossing under Albany Street; to the Stoney Brook Sewer, discharging upon the Back Bay flats; and the Muddy Brook Sewer, between Brookline Avenue and Downer St. The tide in the canal was sluggish they pointed out, and the discharge of three or four sewers into it, leaves shallow water at low tide “through which the foul gases from the putrid bottom can be seen bubbling into the atmosphere
SAVEAGE FOR THE BWSC, THE WATER AND SEWER WORKS OF THE CITY OF BOSTON 1630 — 1978.

On this plan the shaded portion represents the original area of the city, and very nearly its limits in 1823. The unshaded portion of the plan, indicating present limits, consists entirely of reclaimed land filled to level planes little above mean high water, the streets traversing such districts being seldom more than seven feet above that elevation. A large proportion of the house basements and cellars in these regions are lower than high water, and many of them are but from five to seven feet above low-water mark, the mean rise and fall of the tide being ten feet.
This lowness of land surface and of house cellars necessitates the placing of housedrains and sewers at still lower elevations. Most house-drains are under the cellar floors, and fall in reaching the street sewers ; the latter must be still lower, and in their turn fall towards their outlets, which were rarely much, if at all, above low water. Moreover, as filling progressed on the borders of the city, it became necessary to extend the old sewers whose outlets would have been cut off. The old outlets being generally at a low elevation, even where the sewers themselves were sufficiently high, the extensions had to be built still lower, and when of considerable length could have but little fall towards the new mouths.
As a consequence, the contents of the sewers were damned back by the tide during the greater part of each twelve hours. To prevent the salt water flowing into them many of them were provided with tide-gates, which closed as the sea rose, and excluded it. These tide-gates also shut in the sewage, which accumulated behind them along the whole length of the sewer, as in a cesspool ; and, there being no current, deposits occurred.
The sewers were, in general, inadequately ventilated, and the rise of sewage in them compressed the foul air which they contained and tended to force it into the house connections. To afford storage room for the accumulated sewage, many of the sewers were built very much larger than would otherwise have been necessary, or than was conducive to a proper flow of the sewage ; and, as there would have been little advantage in curved inverts where there was to be no current, flat-bottomed and rectangular shapes were frequently adopted. Although at about the time of low water the tide-gates opened and the sewage escaped, the latter almost immediately met the incoming tide, and was brought back by it, to form deposits upon the flats and shores about the city. Of the large amount of sewage which flowed into Stony Brook and the Back Bay, and especially that which went into South Bay, between Boston proper and South Boston, hardly any was carried away from the vicinity of a dense population.” (Main Drainage Works, 1885).

Many of the springs, and especially the larger springs in the carbonate geologic terrane of western Massachusetts, are located on or in close proximity to major geologic features such as thrust faults and sinkholes. This proximity strongly suggests that the location and the high yields of some springs in this area are strongly affected by the bedrock structure or lithology.
Characteristics of and Areas Contributing Recharge to Public-Supply Springs in Massachusetts, Bruce P. Hansen and Kirk P. Smith, Mass. DEP, USGS, Water-Resources Investigations Report 03-4266 (2004).

The number of hidden springs, which only came to notice as wells were sunk, was very large; and occasionally great virtues were ascribed to many of them.
A TOPOGRAPHICAL HISTORICAL DESCEIPTION BOSTON. BT NATHANIEL B. SHURTLEFF. BOSTON: PRINTBD BT BEQUEST OF THE CITY COUNCIL. 1871.

"In pre-contact periods, the Massachuseuk dominated a roughly fifteen-mile shoreline from Quinobequin, or Winding Water (now the Charles River) to Patuxet (now Plymouth). Led by the sachem Chickataubut (House of Fire), they were centered at Cohasset, near modern Scituate, with a base at Passonagessit hill, some two miles south of Moswetuset Hummock. The Massachuseuk derived their name from the sacred hill Massa-adchu-es-et, which lies about seven miles inland from the Atlantic. The volcanic formation in question is five miles long, trending east-west, with a spring at the western end that is the source of the Naponset River, a waterway that was the central axis of the Massachuseuk world. The mouth of the river, where the Hummock is located, was called Messatsoosec, “the great hill’s mouth,” and was known for its mollusks. The area between the hills and the shore, in what is now Dorchester, was a corn-growing zone. On the southern edge of the Massa-adchu-es-et is a pond called Ponkapoag, a word thought to mean “sweet water” or “a spring that bubbles from red soil.” This area, protected from northern winds, served as the group’s winter residence."
The “Indianized” Landscape of Massachusetts, https://placesjournal.org/article/the-indianized-landscape-of-massachusetts/

"Artesian Conditions. Natural and man-made artesian conditions have caused failure in the Boston area. The natural ones occur along major buried valleys, four of which extend into the Boston Basin, and roughly correspond to present drainage courses and rivers flowing toward Boston Harbor (Upson & Spencer, 1964). Depths of these valleys extend up to 76.2 meters (250 feet) below mean sea level (MSL). However, glaciers have eroded some of these valleys to produce local enclosed basins (Kaye, 1982b). The unconsolidated deposits within these valleys tend to be locally complex, but the stratigraphy is generally similar to depositional sequences observed elsewhere in the Boston Basin. The valleys are filled typically by sequences of alternating marine clay and outwash, underlain by basal till. Estuarine silt, peat and alluvium commonly form the surficial strata adjacent to present-day streams and their tributaries. Groundwater in the outwash layers is commonly under artesian conditions due to confinement. by relatively impermeable clay or estuarine deposits."

Barosh & Woodhouse, A City Upon a Hill: Geology of the City of Boston & Surrounding Area, Geotechnical Factors in Boston, Civil Engineering Practice, Vol. 26-27 (2011/2012).

Winthrop accepted the invitation, settled the Shawmut Peninsula, and established the town of Boston. Additional springs were located and wells were dug for private and public use; these ground-water supplies met Boston’s needs for about the next 150 years. By the late 1700s, however, the paving of upland ground-water recharge areas on the peninsula had reduced the available water supply, and contamination from privies and livestock had compromised water quality to the point where public health was at risk. Consequently, Boston residents were forced to import drinking water from the mainland to meet their needs.
Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

Found artesian water 80-90 ft down under blue clay and water as cold as ice hit bedrock 10-15ft more, then no spring, then raise pip 8ft, huge spring. For witches pond, drove pipes and found coal and blue clay – vein of coal 100ft down water 1870s learned underground river rolling from one end of the city to the other in Providence but no shared with public until 1890s.
A Subterranean River, Boston Evening Transcript, Sat, Feb 11, 1893, Page 9

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Charles River

The Charles River drains a 268-mi2 area upstream of the Watertown Dam, and has an estimated mean annual streamflow at the dam of about 400 cubic feet per second (ft3 /s; Zarriello and Barlow, 2002). The Charles River watershed upstream of Watertown is relatively flat, contains extensive areas of riparian wetland, In addition to the Charles River, 17 named streams occupy the lower Charles River watershed (table 1). However, Muddy River and the upstream reaches of Stony Brook are the only two streams in the lower watershed identified on maps that are widely available today, such as the U.S. Geological Survey Boston South topographic quadrangle map (U.S. Geological Survey, 1987), or the Massachusetts Geographic Information System’s electronic hydrography coverages (Massachusetts Geographic Information System, 2004). Information about the remaining streams and their watersheds may be found on historic maps or the storm-drain atlases of the lower Charles River municipalities. These drain atlases typically retain the original names of major culverted streams The lower Charles River was originally an estuary that extended over 9 miles inland from Boston Harbor to rapids at Watertown.
Weiskel, Barlow, & Smieszek, Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005, U.S. Geological Survey, Reston, Virginia: 2005

USGS, 1976

Creeks & Springs

"Plentiful freshwater springs and wells on the Shawmut Peninsula played a role in the Puritan's decision to move the colony's new seat of government across the mouth of the Charles River from their initial settlement in Charlestown. Boston's Great Spring was located near the corner of today's Washington & Water Streets, and its importance is shown by the fact that Governor Winthrop built his second house beside it. Another large spring lay on the slopes of Beacon Hill above Beacon Street and shallow wells could be dug by hand in the soft, sandy soil near almost any home."

"Boston's Back Bay : the story of America's greatest nineteenth-century landfill project", Newman & Holton (2006).

1850

"On March 4, 1633, it was “agreed, that the bounds formerly sett out betwixt Boston and Rocksbury shall continue, only Rocksbury to enioy the conveniency of the creeke neere therevnto.” The creek was dredged in later years and became known as Roxbury canal. The “bounds formerly sett out” were a line crossing Washington Street a little north of the old Roxbury burial ground on the corner of Eustis Street, between that and the present Massachusetts Avenue."

How Massachusetts Grew, 1630-1642, A Study on Town Boundaries, Albert Harrison Hall, The Cambridge Historical Society, Publications XIX (1930).

Elderly persons often speak of other boiling springs The number of hidden springs, which only came to notice as wells were sunk, was very large; and occasionally great virtues were ascribed to many of them.
Unfortunately for the proprietor of the mineral spring, a disagreeable story got about, that the well hadi
lost its mineral qualities and medicinal virtues. The source of revenue failed, and in a short time the Boston. Mineral Spring was almost entirely forgotten, and kept only in remembrance by those who had no specially good reason for desiring to forget it, and who occasionally kept it in their minds as a good story of- the uncertainty of some kinds of earthly riches.
A noted spring, endeared to the famous old punch drinkers of the town, was situated just west of West Hill, on the shore of Charles River, and only accessible at low water. The water from this is said to have had special qualities for the manufacture of the once popular beverage called punch, and consequently the spring was much frequented by the jolly fellows of the town, who in days that are past were generally pretty good epicures.
Nathaniel B. Shurtleff, N.B., A Topographical Historical Description Boston.(1871).

It extended back along the south side of Boston separated from the Back Bay by a narrow causeway called "The Neck", which is now Washington Street. Bordering "The Neck" and extending into the Bay were marshes and flats. Boston at that time comprised some 600 acres, and when high tides submerged the causeway or "Neck", the City was isolated from the mainland and became an island. As commerce and industry increased, the City expanded outwards into the marshes and flats... Roxbury Brook was widened and deepened and became a canal capable of handling vessels of all sizes of that period."
A Study for the Development of Fort Point Channel, South Bay, and Adjacent Areas, Port of Boston Authority (1950).

"The road along the Neck crossed low-lying sections of tidal mudflat that were impassable in the spring when horses were forced to wade knee-deep in surging water at full tides."
"Boston's Back Bay : the story of America's greatest nineteenth-century landfill project", Newman & Holton (2006).

"In 1634, Boston made the first allotments of land at Muddy River, but there was no settlement for several years. On January 8, 1638, eighty-six poor families, comprising three hundred and thirty-seven souls, were allowed four and five acres apiece ; and, at the same time, grants of three hundred acres apiece were made to thirty of the principal people of Boston. Among these early grantees were the Rev. John Cotton, Governor Leverett, and Robert Hull, son of the mint master, whose farm passed into the ownership of his more famous brother-in-law, Judge Samuel Sewall. The Judge's farm was in the upper part of the town on Charles River, and its western boundary was Smelt Brook, in consequence of which the farm was called Brookline. Sewall's Point projected into the river ; and in the same vicinity according to ancient maps were many swamps and morasses, one of which was called White Cedar Swamp. It is probable that this was the scene of Irving's story of The Devil and Tom Walker ', which was laid in the "inlet of Charles's Bay. " The land north of Dudley Square, about as far as the present Dover Street and lying between Stony and Smelt brooks, was called Boston Neck. The Neck was a low, marshy tract, which was a favorite place for sportsmen. In early days, however, travellers over the narrow pass often lost their way at night and came to grief in the adjacent marshes, while robberies were frequent. By 1753, it had become so dangerous that the General Court ordered the Neck to be fenced in; and, in 1757, the same body authorized the raising of £2000 by means of a lottery in order to grade and pave the Neck, while, in 1758, another lottery was authorized to raise money to pave the highway from the Boston line to Meeting-house Hill in Roxbury. In 1800, there were not more than three houses between the site of the Catholic Cathedral at Maiden Street and Roxbury, all the others having been destroyed during the siege and not rebuilt. In 1855, Washington Street was widened from the burying-ground to Warren Street. During the American investment of Boston in 1775 and 1776, a line of strong entrenchments and redoubts extended across the Neck from brook to brook near Clifton Place, just north of the boundary line between Boston and Roxbury. The advance line was about one hundred yards in front of these, a little south of Northampton Street and near the George Tavern. All of these redoubts and fortifications were planned and built by Rufus Putnam, Henry Knox, and Josiah Waters. The British had an advanced post near the upper end of the Neck about on the line of Franklin and Blackstone parks, a distance of about a mile from Dudley Square. A few rods beyond the advanced fortifications of the Americans stood the George, or St. George, Tavern. It was outside the Boston town gate, and it stood in a field of eighteen acres. Many of the royal governors were received here by the people. In 1721, the General Court met here on account of the prevalence of smallpox in the city. In 1769, Edward Bardin changed the name to the King's Arms, but the inn did not retain the name very long. Bardin seems to have been partial to this name, for he opened a tavern on lower Broadway, New York, near the Bowling Green, under the same sign. In 1775, the tavern was the centre of military operations, and Washington and his staff visited it frequently for observation of the enemy's redoubts. As it was within easy musket shot of the British line, the distinguished party became objects for the marksmanship of the British. Fortunately, their aim was not good, and, though they hit the house, they did not hit any of the party of observation on any occasion. On the triangular field of six acres lying between Washington, Eustis, and Dudley streets the training field of early days was located; and here, on the first Tuesday of every month, Captain John Underhill used to put the Roxbury train band through its drill. Jesse Daggett, a train band captain, kept a tavern called the Ball and Pin close by at a later time. It was conveniently placed to satisfy the cravings of the militiamen after a hot and dusty drill upon the adjoining field. North of the burying ground was Washington Hall, later Hotel, which was a tavern as early as 1820. Washington House was a little south of the George Tavern, and was for some years a young ladies' school; it was succeeded by Washington Market From the two parks already mentioned, as far as Beach Street, the Neck was so narrow that it often overflowed at high tides, and Roxbury and Boston were cut off from each other, as there was no bridge over the Charles until 1786. The narrowest part of the Neck was at Dover Street. In Captain Nathaniel Urig's account of his visit to Boston in 1710, he says: The Neck of Land betwixt the city and country is about forty yards broad, and so low that the spring tides sometimes wash the road, which might, with little charge, be made so strong as not to be forced, there being no way of coming at it [Boston] by land but over the Neck. On the site of the old fortification and near it are now
Jenkins, Stephen, The Old Boston Post Road, New York, G. P. Putnam's sons, (1913).

An act changing the boundary line between Boston & Roxbury, making the center of Hammond street the boundary line instead of the thread of the creek, was passed April 3, 1860
(Chap. 172, Acts of 1860), provided, however, that the line be accepted by the city councils of Boston and Roxbury. Passed May 8, 1860. See CC 906, Engineering Department (Surveying Division).

Roxbury canal, Rox., 179G; from the northeasterly side of :Massachusetts avenue, midway between Albany street and Southampton street, to South Bay; formerly canal, 50 feet in width, extending from the wharf at Lamb's dam (just north of Northampton street) nearly to Eustis street, directly back of the burying ground. It was built by the" Proprietors of Roxbury Canal," who were incorporated in 1796 for the purpose of opening a communication by water upon the easterly side of the town of Roxbury, to extend into Roxbury; and under their charter straightened and excavated a creek which ran through Lamb's dam farm and the marsh adjoining, and constructed "·hat was known as Roxbury canal. A portion of the former boundary line between Boston and Roxbury formerly ran through the middle of this canal. The portion lying south of Lamb's dam was discontinued and filled in 1820, the direction of the remaining portion was diverted and a new portion dug at that time, having its terminus at a point about 50 feet east of Harrison avenue, midway between Northampton street and Massachusetts a venue. On June 30, 1868, Albany street in Roxbury was extended across Roxbury canal and Roxbury Town wharf or landing place to Northampton street. A bridge was built across the canal, within the lines of Albany street, by an order of the Boston City Council approved, Oct. 2, 1868; the bridge was completed and open for travel early in 1869. The canal was Declared a nuisance, and under chapter 217 of the Acts of the Legislature the city was authorized to fill the territory bounded by Harrison avenue, East Chester park (now Massachusetts avenue), Swett (now Southampton) street and Northampton street, which included a portion of the canal. The filling was begun in 1878; the bridge was probably removed in 1879, and the canal south of Massachusetts avenue completely filled in 1880. See L 1311, L 1331; Vol. 40, pp. 4, 14, CC. 146; City Doc. 92, 1877.
LIST OF STREETS, ETc., IN BOSTON

The inhabitants of this towne, were the first that set upon the trade of fishing in the Bay, who received so much fruite of their labours, that they encour- aged others to the same undertakings. A mile from this Towne lieth Roxberry, which is faire and handsome Countrey-towne; the inhabitants of it being all very rich. This Towne lieth upon the Maine, so that it is well woodded and watered; having a cleare and fresh Brooke running through the Towne: In which although there come no Alewiues, yet there is great store of Smelts, and therefore it is called Smelt-brooke. A quarter of a mile to the North-side of the Towne, is another River called Stony-river; upon which is built a water-mille. Here is good ground for Corne, and Medow for Cattle : In westward from the Towne it is something rocky, whence it hath the name of Roxberry; the inhabitants have faire houses, store of Cattle, impaled Corne-fields, and fruitful! Gardens. Here is no Harbour for ships, because the Towne is seated in the bottome of a shallow Bay, which is made by the necke of land on which Boston is buUt; so that they can transport all their goods from the Ships in Boats from Boston, which is the nearest Harbour. This necke of land is not above foure miles in compasse, in forme almost square, having on the south-side at one corner, a great broad hill, whereon is planted a Fort, which can command any ship as shee sayles into any Harbour within the still Bay. On the North-side is another Hill, equall in bignesse, whereon stands a Windemill. To the North-west is a high Mountaine with three little rising Hils on the top of it, wherefore it is called the Tramxmnt. From the top of this Mountaine a man may over-looke all the Bands which lie before the Bay, and discry such ships as are upon the Sea-coast. This Towne although it be neither the greatest, nor the richest, yet it is the most noted and frequented, being the Center of the Plantations where the monthly Courts are kept. Here likewise dwells the Governour: This place hath very good land, affording rich corne-fields, and fruiteful Gardens ; having likewise sweete and pleasant Springs. The inhabitants of this place for their enlargement have taken to themselves Farme-houses, in a place called Muddy-river, two miles from their Towne; where is good ground, large timber, and store of Marsh land, and Meadow. In this place they keepe their Swine and other Cattle in the Summer, whilst the Come is on the ground at Boston, and bring them to the Towne in Winter."
A TOPOGRAPHICAL HISTORICAL DESCEIPTION BOSTON. BT NATHANIEL B. SHURTLEFF. BOSTON: PRINTBD BT BEQUEST OF THE CITY COUNCIL. 1871.

Port Point was situated near Rowe's Wharf, east of Fort Hall, and took its name from its proximity to the first fort erected on the peninsula. It gave name to the channel passing by it, which led from the bay just east of Dover Street Bridge. This bay has at times been known as Roxbury Harbor, Gallows Bay, and more recently as South Bay; while the channel has been known as Fort Point Channel, although sometimes it has been called erroneously Four Points or Fore Point Channel. After the Sconce was built at this Point it took the name of Sconce (or South Battery) Point.
A TOPOGRAPHICAL HISTORICAL DESCEIPTION BOSTON. BT NATHANIEL B. SHURTLEFF. BOSTON: PRINTBD BT BEQUEST OF THE CITY COUNCIL. 1871.

The confluence of Stony Brook, Muddy River, and the Charles River, as it existed in the early 19th century, and the subsequently constructed area of the Back Bay Fens, about 1903. The tidal waters west of Gravelly Point had become severely polluted with sewage by the 1870s. The “Smelt Brook” shown above is presently within Boston’s combined-sewer drainage area, and therefore is not depicted (Freeman, 1903).
Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

1873 Open lots on West Chester Park

"It being a necke and bare of wood: they are not troubled with three great annoyances, of Woolves, Rattle-snakes, and Musketoes. These that live here upon their Cattle, must be constrayned to take Farmes in the Countrey, or else they cannot subsist; the place being too small to containe many, and fittest for such as can Trade into England, for such commodities as the Countrey wants, being the chiefe place for shipping and merchandize. This necke of land is not above foure miles in compasse, in forme almost square, having on the south-side at one corner, a great broad hill, whereon is planted a Fort, which can command any ship as shee sayles into any Harbour within the still Bay. On the North-side is another Hill, equall in bignesse, whereon stands a Windemill. To the North-west is a high Mountaine with three little rising Hils on the top of it, wherefore it is called the Tramxmnt. From the top of this Mountaine a man may over-looke all the Bands which lie before the Bay, and discry such ships as are upon the Sea-coast. This Towne although it be neither the greatest, nor the richest, yet it is the most noted and frequented, being the Center of the Plantations where the monthly Courts are kept. Here likewise dwells the Governour: This place hath very good land, affording rich corne-fields, and fruiteful Gardens ; having likewise sweete and pleasant Springs. The inhabitants of this place for their enlargement have taken to themselves Farme-houses, in a place called Muddy-river, two miles from their Towne; where is good ground, large timber, and store of Marsh land, and Meadow. In this place they keepe their Swine and other Cattle in the Summer, whilst the Come is on the ground at Boston, and bring them to the Towne in Winter."
TOPOGRAPHICAL AND HISTORICAL...

"Fort Point Channel and South Bay constitute an estuary of Boston Harbor approximately two miles long serving as a natural water barrier separating Boston Proper and South Boston. South Bay, which extends from Massachusetts Avenue to the Dover Street Bridge, has as its upper extremity a shallow channel known as Roxbury Canal. Fort Point Channel is defined as the waterway extending below the Dover Street Bridge to the inner harbor at Northern Avenue. At a point approximately halfway between Dorchester Avenue Bridge and Massachusetts Avenue the Dorchester Brook, a branch estuary, discharges into the easterly side of South Bay in an irregular open channel."

1959 Senate Bill 0498. Report of the Special Commission Relative to Filling and Improving South Bay and Part of Fort Point Channel in the City Of Boston: A Comprehensive Report for the Filling and Improving a Portion of Fort Point Channel and South Bay. (1959).

"The primary and literally life-giving element was the abundant water available to the settlers. The Shawmut Peninsula became the
Town of Boston because of sweet and pleasant springs, along with water of good quality under artesian pressure from shallow dug wells. Much of the area is underlain by a sandwich of thick, pervious sand and gravel between lodgement till and marine clay, and the thick deposits beneath Beacon Hill fed reliable springs at its base."

Barosh & Woodhouse, A City Upon a Hill: Geology of the City of Boston & Surrounding Area, Settlement, Topography & Geologic Studies of Boston, Civil Engineering Practice, Vol. 26-27 (2011/2012).

"There is a substantial amount of ground water in the subsoil throughout the area under investigation which tends to maintain the summer or dry-season flow in the upland waterways. This infiltration of ground water into sewers appears to be relatively large."

Report of the Special Commission Investigating Systems of Sewerage and Sewage Disposal in the North and South Metropolitan Sewerage Districts and the City of Boston, Commonwealth of Massachusetts House, (June 15 1939).

"Plentiful freshwater springs and wells on the Shawmut Peninsula played a role in the Puritan's decision to move the colony's new seat of government across the mouth of the Charles River from their initial settlement in Charlestown. Boston's Great Spring was located near the corner of today's Washington & Water Streets, and its importance is shown by the fact that Governor Winthrop built his second house beside it. Another large spring lay on the slopes of Beacon Hill above Beacon Street and shallow wells could be dug by hand in the soft, sandy soil near almost any home."
"The road along the Neck crossed low-lying sections of tidal mudflat that were impassable in the spring when horses were forced to wade knee-deep in surging water at full tides."
Stony Brook and Muddy River, tidal drainage channels, and small creeks could "float small boats at high tide."
"Boston's Back Bay : the story of America's greatest nineteenth-century landfill project", Newman & Holton (2006).

The Native American community of the watershed continuously occupied the area for the at least 4,000 years. The community was decimated by an epidemic, in the 1610s. In 1630, the first large group of English settlers, led by John Winthrop, arrived at the Shawmut Peninsula to establish a colony and the town of Boston. Almost immediately, the settlers of Boston and adjacent towns also began to modify the landscape and water resources of the watershed.
Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

Boston Hydrology

Ground-water levels on Boston peninsula, Massachusetts, Hydrologic Atlas 513, (1975), https://pubs.usgs.gov/publication/ha513

USGS, 1976

Muddy river and STormy Creek

Confluence of Charles River, Muddy River, and Stony Brook Creek

1903, Fens Basin, "Old Stony Brook Conduit Outlet, Outlet of Fens Basin"

1892, Muddy River, Sears Park

1874_Sixth_Ward_Vol1_Plate_Z_29_Mill_Dam

1855, Cross Dam

1880

1882	1873, Cross Dam

The first and oldest of the well-determined water bodies was Lake Bouve, which, according to Grabau,3 covered an area south of Boston Harbor and extended across Braintree and Weymouth into Hingham. It was 12 miles long and about 140 feet above sea level. 3 According to Clapp 4 this was followed by Charles and NVponset lakes at 240 feet, tributary, respectively, to Taunton and Blackstone rivers, and which at 200 feet were confluent and discharged into Taunton River. Clapp states that later, as Charles Neponset Lake, at 160 feet, it discharged into Lake Bouve and that it extended eastward across Wellesley and Needham into Newton and West Roxbury and northward into Billerica. Crosby 1 states that north of Lake Bouve was Lake Shawmut, which extended northward across Boston Harbor and westward to Milton. He holds that an ice lobe continued to advance southward in the basin of Boston and Massachusetts bays while the ice margin farther west was being melted back for some distance. Thus the drainage eastward was impounded and the bottom of Lake Shawmut was covered with thick laminated blue clays. Northwest of Lake Shawmut, according to Goldthwait,2 was Lake Sudbury, which, at different stages, stood at altitudes of 195 to 160 feet above sea level. It extended from South Framington to Weston and from Concord to Wellesley.
GEOLOGY OF MASSACHUSETTS AND RHODE ISLAND, https://pubs.usgs.gov/bul/0597/report.pdf

Mill Dam & Smelt Creek

Mill Dam closed off the wide, north facing mouth of Back Bay. The dam was built along the line of present-day Beacon Street to Kenmore Square, and much of it is still buried under the street. The shorter "Cross Dam" connected the end of Gravelly Point with the Mill Dam roughly where Mass. Ave. runs today from Boylston St to Beacon St. The full Basin lay west of the Cross Dam.
"Boston's Back Bay : the story of America's greatest nineteenth-century landfill project", Newman & Holton (2006).

"From 1822 to 1858, a “perpetual power” system supplied continuous, uniform tidal power to Boston industries. A 2.4 km dam in the Charles River estuary and a shorter cross dam formed two basins. Industries drew water from a “full” basin that was replenished at high tide, passed it through breast wheels, and discharged it to a “receiving” basin that emptied at low tide. Unlike owners of conventional, intermittent tide mills, who sold services or products, the managers of this system sold energy to industrial customers, as modern utilities do. They created new opportunities for Boston’s inventors and artisans, and the roads built on their dams became important transportation links for the city. Yet the project also degraded the estuarine environment and generated complaints about pollution. When population growth and falling costs for steam power made the extensive basins and mill sites more valuable for urban development than for generating renewable energy, a novel earth-moving process filled the basins to form Boston’s prestigious Back Bay district. This little-known, unique tidal-power development overcame daunting technological challenges in a period when American civil engineering was in its infancy."
Gordon, Robert & Malone, Patrick. (2019). “Perpetual power” from the tides in Boston, Massachusetts, USA, 1813–1858. Water History. 11. 10.1007/s12685-019-00228-1.

The confluence of Stony Brook, Muddy River, and the Charles River, as it existed in the early 19th century, and the subsequently constructed area of the Back Bay Fens, about 1903. The tidal waters west of Gravelly Point had become severely polluted with sewage by the 1870s. The “Smelt Brook” shown above is presently within Boston’s combined-sewer drainage area, and therefore is not depicted (Freeman, 1903).
Weiskel, Barlow, Smieszek; Water Resources and the Urban Environment, Lower Charles River Watershed, Massachusetts, 1630–2005; US Dept. of the Interior, US Geology Survey, Circular 1280 (2005).

Smelt Brook, which was much prized for its pure water, ran at the west of the ridge at Tommy's Rock, then across Washington Street and Guild Row, and "lost it self in the marshes" to the north of the town. Farther to the west Muddy River ran from Jamaica Pond in a tortuous course and emptied into Shallow Bay. The Dudley Estate extended west nearly to the Meeting House, the boundary being Smelt Brook. The Dudley mansion stood opposite Guild Row.

"In 1814, a man who has since been called the “Chief Benefactor of Boston” had an idea. It was so stupendous that it was then considered a weird, impossible dream. Yet the train of consequences resulting from that idea have been largely responsible for Boston’s greatness today. One hundred and twelve years ago, Uriah Cotting, on behalf of a group of men who together formed the Boston and Roxbury Mill Corporation, applied to the legislature of Massachusetts for a charter which should empower the Company to build a series of dams connecting Boston, Brookline, and Roxbury; to use these dams as toll roadways, and to develop water power by the tidal flow in and out of the Back Bay. This Bay was so called to distinguish it from the harbor - or Front Bay, and from the South Bay. It was at that time a shallow sheet of water, spotted here and there by marshy islands and flats. Charles Street, Boston Neck, and the Roxbury mainland marked the shore line, but when the tide was unusually low much of the entire expanse was bare. The project of Uriah cotting and his associates marked the first attempt at development in this area. In spite of much opposition, the legislature granted the charter of the Mill Corporation, slipping it through rather secretly at a session when only fifty members were present. Governor Strong signed the bill, and work was soon begun. The Mill Dam was built from the Common at the foot of Beacon hill to the solid land at Sewall’s Point, now the junction of Brookline and Commonwealth Avenues. It was a toll thoroughfare, today known as Beacon Street. When first opened to travel it formed a new, short way between Boston, the Brighton road, and the Punch Bowl road, which ran westward from the outer end of the dam. It was here that the famous Punch Bowl Tavern was located. The stream of traffic that passes through Governor Square today represents the growth during many years of that which flowed over the old Mill Dam highway. Connecting the Mill Dam with Gravelly Point - a promontory extending from Roxbury to what is now the corner of Massachusetts and Commonwealth Avenues - was built the Cross Dam. The two enclosed the power company’s receiving basin. In the neighborhood of Gravelly Point, the Roxbury town landing had been located. With the completion of the Cross Dam and the availability of water power, the Point became the center of a manufacturing community. Near here were grist mills, soap and candle works, a fulling mill, a looking glass and a carpet works. Today Gravelly Point is still the center of a business community. Despite the passage of years and a multitude of changes, we see in the Massachusetts Avenue neighborhood the development of the old-time Cross Dam Community. Uriah Cotting did not live to see his project completed. He was succeeded by Loammi Baldwin, who finished, in 1821, the construction of the dams. The area enclosed by them formed a tidal basin which soon became a nuisance, an eyesore, and a menace to the health of the city. The building of railways and dissatisfaction among the mill interests with the available power foretold further development. The public voice began to urge that the flats of the basin be filled in and new land be made, as had already been done along the harbor front. By 1844, two railroads had been laid across the flats - the Boston and Worcester Railroad and the Boston and Providence line. The rails of these lines could be used to transport material - “clean gravel and earth” - easily and cheaply. By making use of the dams as retaining walls, sand dredged from the bed of the Charles River could be used to make land on the flats. Several plans for the development of the district were proposed, and, in 1852, a legislative committee recommended that the district be filled in. That the narrow and winding streets of the older city somewhat preyed on the minds of the citizens is realized when it is observed that the new district was to be “laid out in rectangular plots, with wide streets.” Ordinary streets were to be a hundred feet wide between buildings, while the central boulevard - Commonwealth Avenue - was to have the unprecedented width for Boston of two hundred and forty feet! Imagine the meaning of this to those who could hardly even conceive a street over thirty feet wide. It was the accepted program that the State should pay for the work of filling in the basin, and should be repaid by the sale of the new land. Certain lots were to be set aside for museums, schools, charities, and so forth. Other spaces were to be left for parks and playgrounds, and the balance to be sold for residences. But before actual work could be begun, there was much wrangling and disagreement. The town of Roxbury, perhaps a bit jealous of her larger neighbor, refused at first to disclaim title to the bottom lands within her boundaries. The powerful water power company held out for better terms. Petty bickerings and politics delayed operations several years, but finally, in 1859, the Back Bay was attacked with sand, gravel, and earth. Progress was slow. By 1874, the dry land extended only as far out as Gloucester Street. As the filled area increased size, building went on apace. The fashionable families began to desert the South End for new and magnificent homes along the wide, parked streets of the newly made section. The name Back Bay, instead of an epithet applied to a sheet of shallow water and mud flats, became a synonym for fashion and culture. Beacon Street - the former Mill Dam - was soon lined with the now familiar brown stone homes. The parallel streets were given the names that in the early days had been given to parts of Washington Street - Newbury and Marlborough. Commonwealth Avenue soon began to take on an atmosphere of luxury a bit above its neighbors. Clubs and hotels appeared - and the back bay was Back Bay. The finishing touches at the Fenway were added between 1882 and 1885, marking the first step in the famous Metropolitan Park system of Boston. For a decade or more the pressure in the congested downtown section of Boston has caused many to seek a business home in the wider spaces of the newer city. Very gradually trade has crept westward into Back Bay. New business centers have grown up in the neighborhood. The modern apartment house has, in many cases, displaced the residence of the ‘70’s. Recognizing the trend of the times, the Old Colony Trust Company has established a new office to serve this growing neighborhood. This office occupies the ground floor of a fine new building at the corner of Massachusetts and Commonwealth Avenues, on the exact spot where the old Cross Dam joined the mainland at Gravelly Point, the only bit of lower Commonwealth Avenue that is not man-made land."

"Building the Back Bay", The Old Colony Trust Company, Boston MA, 1926

The Boston and Roxbury Mill Corporation (BRMC) was incorporated in 1814 to build a dam across the tidal marsh lands of the Charles River in Boston in order to produce power for mills. Begun under the direction of engineer Uriah Cotting and completed by Loammi Baldwin, the dam and the toll-road on top of it (later to become Beacon St.) was completed in 1821. In 1824, stockholders organized the Boston Water Power Company (BWPC) to handle mill franchises and water rights, but after railroad tracks crisscrossed the basin in the 1830s and 1840s, the project proved impractical. By 1857, the BRMC, the BWPC, and the Commonwealth of Massachusetts began filling in the basin, which became the Back Bay section of Boston, and ownership of the land was divided between the three entities. BRMC continued to build roads, houses, and other structures on their land, which included present-day Beacon St., Brookline Ave., Commonwealth Ave., and Kenmore Square, until the 1890s. The records in this collection reflect the activities of the corporation, its directors, superintendents, and stockholders, relating primarily to its varied construction and building projects.
https://www.masshist.org/collection-guides/view/fa0342

"Immediately north of the Neck and west of the peninsula lay salt marshes and mudflats exposed at low tide sliced by braided networks of stream channels of the river estuary. Originally 737.5 acres in extent, the bay was unequally divided by a small promontory called Gravelly Point (in the vicinity of today's Massachusetts Avenue) that left the largest portion to the east. The embayment eventually succumbed to the the city's growing pains by being filled in as did the cove on the south side. On the south side of the peninsula, between The Neck and Dorchester Point/Neck were South Cove and South Bay. After filling in that began in the late eighteenth century, the area became the Leather District, Chinatown and the confusion of "Big Dig" ramps to Fort Point Channel, which is a stunted river-like remnant of South Bay.

Reminiscent of the Mill Pond, Back Bay's filling began as a power project, when, between 1818 and 1821, an ambitious dam was built by the Boston and Roxbury Mill Corporation. The one and a half mile-long Great Dam extended across Great Bay - the embayment of the Charles River - from the foot of the Common (intersection of Charles and Beacon Streets) on the east to Sewall Point in Brookline (Kenmore Square) on the west. It was intersected by a shorter cross-dam that ran from the low peninsula of Gravelly Point (today's intersection of "Mass" and "Comm" Avenues). The two dams divided Great Bay in two. Upriver on the west was Full Basin that received water at high tide through five pairs of floodgates. Water was then shunted through sluices to power mills located on Gravelly Point and then through raceways at low tide to a larger Receiving Basin downriver (the part that is known as Back Bay), and finally back out to the main river. The intent was to power the mills to serve and give Boston a competitive edge over steam-powered mills in New York and Philadelphia, while costing less than obtaining items from Europe in short supply from the War of 1812. "

https://written-in-stone-seen-through-my-lens.blogspot.com/2017/02/urban-geology-part-i-filling-in-of.html

1873

Stony Brook Outflow

Stony Brook and Muddy River, tidal drainage channels, and small creeks could "float small boats at high tide."
"Boston's Back Bay : the story of America's greatest nineteenth-century landfill project", Newman & Holton (2006).

"The border through the back bay had been set to follow a channel that cut through shallow tidal flats. And that channel ran quite close to the Boston shore. When the Mill Dam was built from Boston to Brookline to enclose the bay and run tidal mills, Beacon street was extended across it, and Boston was given possession of the new-made land. The above Boston-Roxbury border was a straight-line adjustment of the original meandering border that had been formed by the path of the channel that ran out from the Stony brook outflow to the deeper bed of the Charles river. So what was to be done, when the whole point of the land-making operation was to create a residential for well to do Boston residents? Between the state, which would claim a portion of the new lands for itself, to be sold at a profit, and the city, seeking an extension of its own area to prevent what might be called Brahmin flight, the two simply stole the Back Bay flats from Roxbury by fiat. Just as in the case of Dorchester Heights/South Boston at the start of the century (discussed in an earlier entry), there was money to be made, and the state and city joined hands in a profitable land grab from a bordering town. "
zhttps://goodoldboston.blogspot.com/2011/04/boston-steals-back-bay-from-roxbury.html

Stony Brook Conduit was built in the 1880s and is 3.4km long. Its lined diameter is 5.2x4.7 m, and its 10-15m deep. It runs from West Roxbury to Back Bay and is designated a sewer tunnel. Woodhouse & Barash (1991)

Barosh & Woodhouse, Boston Area Water Supply & Wastewater Tunnels, Civil Engineering Practice (2011/2012)

Stony Brook Culvert/Tunnels

1905

1864

1876

1880

1874

Harbor

1894 – US Army Chief of Engineers report to Sec of War re FPC “If (Fort Point Channel) connects the tidal basin of South Bay, which has an area of 250 acres, with Boston inner harbor, is fast becoming the center of the city’s most extensive shipping trade and is the most important branch of the main ship channel. Before improvement the least depth at mean low water was 12ft at its entrance and 17ft above Congress St Bridge. The project for this improvement was submitted Jan 27 1885. It proposed the excavation of a channel 175 ft wide and 23 ft deep at mean low water… a distance of 4100 feet.” Money for the improvement was allotted in Aug. 1886. Boston Evening Transcript Mon, Jan 14, 1895 ·Page

Hydrographic Survey In the Boston Area: Mineralogy of a Few Sediment Samples from Boston Harbor, Office of Naval Research (1952).

“Boston lies at the head of a broad, island-studded harbor, formed by a deep indentation in the coastline of Massachusetts”
Kaye, C. A., The Geology and Early History of the Boston Area of Massachusetts, A Bicentennial Approach, Geological, Survey Bulletin 1476 (1976).

Fort Point Channel separates Boston proper from South Boston. A dredged channel leads from the entrance to the Summer Street Bridge. (NOAA, U.S. Coast Pilot 1, Chapter 11, 2025). Boston Harbor is the largest seaport in New England and the principal distributing point for regional commerce. Today, the Fort Point Channel extends from Boston Harbor to the Northern Avenue Bridge in South Boston, a distance of about 1,000 feet. It is 23 feet deep and 175 feet wide. (USACE, Boston Harbor Navigation Project, 2025).

“The South Bay was once 138 acres of wetlands and surface water that was present at the site and surrounding properties.”
Widett Circle Properties, Boston, MA, Prepared by VHB for MBTA, Phase I Initial Site Investigation, Tier Classification, & Phase II Scope of Work (Aug. 9 2024).

Physical Setting
Boston Harbor is on the western edge of Massachusetts Bay. The bay is nearly longitudinal and can be found in the vicinity of 424N, 70'W. The bay is approximately 100 km long and 40 km wide and is located in the Gulf of Maine. Boundaries of the bay extend
north to Cape Ann, south to Cape Cod, and east to the eastern coast of Massachusetts (Fig. 1-1). The average depth of the bay is 35 m. The chief topographic feature is a submarine ridge rising within 20 m of the sea surface along the open ocean boundary. This ridge is named Stellwagen Bank (Fig. 1-1). The Stellwagen Bank increases tidal velocities as the waves cross this ridge and head towards shore. The harbor (Fig. 1-2) topography is characterized by two shipping channels (President Roads and Nantasket Roads) and several small islands scattered throughout the harbor. The harbor is relatively shallow (1-10 m) with depths reaching 20 m in the
channels. Flow enters and leaves the harbor primarily through the two channels (Fig. 1-3 1-6), which results in a complex circulation pattern. The harbor begins to stratify in May and is stably stratified by late July. In September, cooling begins and the thermocline deepens until November when the fall overturn begins. In December, the overturn continues and the entire water column is
isothermal. The water column remains isothermal, with the coldest temperature occurring in February, until April when spring warming begins. A profile of the average annual temperature in Massachusetts Bay is shown in Figure 1-7.

The harbor experiences semi-diurnal tidal oscillations with a mean tidal range of 3m. Tidal flow dominates the water exchange, with nearly half of the volume of the harbor leaving on the outgoing tide. The volume exchange during each tidal cycle is approximately 1.1 x 108 m3/day (Kossik et al., 1986). The volume of freshwater flow is small in comparison to tidal action and does not have a significant effect on flushing in the harbor except perhaps during spring runoff periods (Resource Analysis, Inc., 1976). Kossik et al., (1986) showed that the flushing time in the harbor is one-to-two weeks.

The Atlantic Ocean has a significant role in moderating the effects of the winter cold and summer heat. The wind is predominantly westerly with an average wind speed of 20 km/hr, although, it is highly variable (Fig 1-9). Hurricanes and coastal storms bring
significant amounts of rain and snow. Wind-driven currents and tidal activity play a significant role in the mixing and transportation of nutrients and toxins within the harbor. Boston Harbor has a complex system of currents dominated by a southward flow across the mouth of the bay due to- the Gulf of Maine. The flood tides are westerly and the edd tides are easterly (Fig. 1-10).

"Boston Harbor has been the site of waste disposal since before the Revolutionary War."

R89-25 TECHNOLOGY AND POLICY ISSUES INVOLVED IN THE BOSTON HARBOR CLEANUP, RALPH M. PARSONS LABORATORY
HYDRODYNAMICS AND COASTAL ENGINEERING, Report Number 327, November 1989

Gulf of Maine & The Atlantic Canyons

The Gulf of Maine is a marginal sea that is nearly cut off from the Atlantic Ocean by Georges and Browns Banks. The gulf is well known for its anomalously cold waters, a fact that is primarily attributed t the gulfs location in the lee of the North American continent and to the shoal offshore banks that isolate and insulate the gulf b m the warmer waters of the Atlantic (Fig.1). The principal connection between the gulf and the Atlantic is the Northeast Channel, a glacially scoured valley with a sill depth of about 230 m that cuts across the continental slope and divides the banks. The shallower Great South Channel, with a sill depth of about 70 m, is a comparatively gentle depression in the shelf topography that allows a more limited exchange between waters of the gulf and Nantucket Shoals. Relatively fresh and cool water entering the gulf from the Scotian Shelf and fresh water from rivers contrasts with warm and salty Atlantic slope water that flows in through the Northeast Channel as an intermittent bottom current. The resulting water property distributions and estuarine-like circulation are complicated by rugged topography, tidal mixing, seasonal atmospheric interactions, and the influence of the Earth's rotation.
Inside the gulf, the complex bottom topography defines three major basins - Georges, Jodan and Wilkinson - separated at the 200 m depth by various topographic rises and banks. Jordan and Wilkinson Basins have maximum depths of about 275 m, but Georges Basin, which forms the inner terminus of the Northeast Channel, contains the greatest water depth in the gulf at 379 m. Deep water access to the inner basins is controlled by several sills, notably Truxton Swell on the north side of Georges Basin and Lindenkohl Sill (indicated by the "L" in Fig. 1) on the west side of Georges Basin. These sills evidently play an important role in the seasonal evolution of the circulation by controlling the spreading of denser water fiom the continental shelf outside the gulf.

The Non-tidal Circulation
The non-tidal circulation in the Gulf of Maine is basically an anti-clockwise gyre that is severely distorted by bottom topography and seasonally modulated by interactions with the atmosphere and the waters of the Atlantic continental margin. The fmt comprehensive description of the circulation was given by Bigelow (19271

A Brief Overview of the Physical Oceanography of the Gulf of Maine, David A. Brooks, Department of Oceanography, Texas A&M University

MA Bay Bathymetry | Boston Harbor

MA Bay Bathymetry

Three large submarine canyons, Oceanographer, Gilbert, and Lydonia, indent the U.S. Atlantic continental shelf and, with four additional canyons, dissect the continental slope in the vicinity of Georges Bank. On the upper rise, these canyons merge at a water depth of approximately 3100 m to form only two valleys. Differences in channel morphology of the canyons on the upper rise imply differences in relative activity, which is inconsistent with observations in the canyon heads. At present, Lydonia Canyon incises the upper rise more deeply than do the other canyons: however, seismic-reflection profiles show buried channels beneath the rise, which suggests that these other six canyons were periodically active during the Neogene. The rise morphology and the thickness of inferred Neogene- and Quaternary-age sediments on the rise are attributed to the presence and activity of the canyons. The erosional and depositional processes and the morphology of these canyons are remarkably similar to those of fluvial systems. Bear Seamount, which has approximately 2000 m of relief on the rise, has acted as a barrier to downslope sediment transport since the Late Cretaceous. Sediment has piled up on the upslope side, whereas much less sediment has accumulated in the “lee shadow” on the downslope side. Seismic-reflection profile data show that Lydonia Canyon has not eroded down to the volcanic rock of Bear Seamount.
Role of submarine canyons in shaping the rise between Lydonia and Oceanographer canyons, Georges Bank; Marine Geology, (Jan. 1 1985). 10.1016/0025-3227(85)90120-3

The carving of submarine canyons into the continental shelf is poorly understood relative to river valleys on land. We studied a submarine canyon in Northern California that is connected through littoral transport to river sediment using a combination of seafloor mapping, tracking sediments using their chemical elements, and simulating waves and currents to better understand which processes are responsible for canyon erosion. Our findings suggest that canyon focusing of wave energy and an abundant supply of coarse sediment cause erosion at the canyon’s head. This finding helps explain why submarine canyon channel networks erode toward shore and predicts that canyons near mountain ranges will preferentially remain connected the shoreline.
Smith, M. E., Werner, S. H., Buscombe, D., Finnegan, N. J., Sumner, E. J., & Mueller, E. R. (2018). Seeking the shore: Evidence for active submarine canyon head incision due to coarse sediment supply and focusing of wave energy. Geophysical Research Letters, 45, 12,403–12,413. https://doi.org/10.1029/ 2018GL080396
Yu, Fengyize et al. “A global scale submarine landform dataset driven by terrain knowledge.” Scientific data vol. 12,1 870. 27 May. 2025, doi:10.1038/s41597-025-052

Honda, Isabel & Medeiros, Lucas & Thompson, Cameron & Britten, Gregory & Runge, Jeffrey & Ji, Rubao. (2025). Seasonal trophic controls drive population variability in a foundational marine copepod. Scientific Reports. 15. 10.1038/s41598-025-19919-2.

The water mass structure in the Gulf of Maine has been studied by Hopkins and Garfield (1979), Brown and Irish (1993) and others. Analyses of data sets indicate the presence of the following three interior water masses: Maine Surface Water (MSW), Maine Intermediate Water (MIW), and Maine Bottom Water (MBW). Three main boundary water masses are also present: Scotia Shelf Water (SSW), Georges Bank Water (GBW), and Slope Water (SLW, upper and lower).
The distribution of the water masses in temperature, salinity, and depth space show a degree of variability that inhibits the definition of absolute temperature and salinity ranges (Hopkins and Garfield, 1979). The variability can be due to a particular data set, the season (Brown and Irish, 1993) or inter-decadal variation (Colton, 1968). The water mass identification has to be based on the overall physical picture consisting of the temperature and salinity distribution together with the dynamical picture and structures that are at play.
Gangopadhyay et al. (2003) have summarized the synoptic circulation system in the Gulf of Maine and Georges Bank region using a feature-oriented approach. Prevalent oceanographic circulation structures are identified from previous observational studies, also known water mass characteristics and relevant dynamical processes responsible for formation and maintenance of the synoptic features are noted. Features include the buoyancy-driven Maine Coastal Current (MCC), the Georges Bank anticyclonic frontal circulation system, the basin-scale cyclonic gyres (Jordan, Georges, and Wilkinson), the deep inflow through the Northeast Channel, the shallow outflow via the Great South Channel, and the shelf-slope front (see Fig. 1).
The interior Gulf of Maine has three cyclonic circulation regions situated over three deep basins: Georges, Jordan and Wilkinson (see Fig. 1). These gyres are set up by the deep inflow of saline waters through the Northeast Channel, and they are forced by topography (Hannah et al., 1996; Lynch, 1999). In addition, it has been observed that the dominant temporal variability in or between the gyres corresponds to the order of months (Xue et al., 2000).
Among the three basins, Wilkinson Basin area is the farthest away from the inflow region of the Northeast Channel and nearest to the outflow region through the Great South Channel. Furthermore, the underlying topography in this basin is fragmented, as compared to those in the Jordan and Georges Basins. Such physical constraints trigger vigorous water mass transformation processes in this particular basin throughout the year. In particular, the heavy vertical mixing that occurs in this basin (Brown and Irish, 1993) in the winter between the fresh MSW and the saltier MBW results in a water mass called ‘MIW’. In the spring, coastal runoffs from rivers result in fresher surface water, and in the summer, solar heating stratifies the upper layers to produce a varied combination of water masses in the basin over time.
Wilkinson Basin area water masses: a revisit with EOFs, Continental Shelf Research, Volume 25, Issue 2, Pages 277-296 (January 2005).

The Northeast Canyons and Seamounts National Monument consists of approximately 4,913 square miles (12,724 square kilometers) and is located about 130 miles east-southeast of Cape Cod. Approximately the size of Connecticut, the monument includes two distinct areas, one that covers three canyons and one that covers four seamounts. These undersea canyons and seamounts contain fragile and largely pristine deep marine ecosystems and rich biodiversity, including important deep sea corals, endangered whales and sea turtles, other marine mammals and numerous fish species.
The Canyons Unit includes three underwater canyons -- Oceanographer, Gilbert, and Lydonia -- and covers approximately 941 square miles. The canyons start at the edge of the geological continental shelf and drop from 200 meters to thousands of meters deep. In Oceanographer, Gilbert, and Lydonia canyons, the hard canyon walls provide habitats for sponges, corals, and other invertebrates that filter food from the water to flourish, and for larger species including squid, octopus, skates, flounders, and crabs. Major oceanographic features, such as currents, temperature gradients, eddies, and fronts, occur on a large scale and influence the distribution patterns of such highly migratory oceanic species as tuna, billfish, and sharks. They provide feeding grounds for these and many other marine species.
The New England Seamount Chain was formed as the Earth's crust passed over a stationary hot spot that pushed magma up through the seafloor, and is now composed of more than 30 extinct undersea volcanoes, running like a curved spine from the southern side of Georges Bank to midway across the western Atlantic Ocean. Many of them have characteristic flat tops that were created by erosion by ocean waves and subsidence as the magma cooled. Four of these seamounts -- Bear, Physalia, Retriever, and Mytilus -- are in the United States Exclusive Economic Zone. Bear Seamount is approximately 100 million years old and the largest of the four; it rises approximately 2,500 meters from the seafloor to within 1,000 meters of the sea surface. Its summit is over 12 miles in diameter. The three smaller seamounts reach to within 2,000 meters of the surface. All four of these seamounts have steep and complex topography that interrupts existing currents, providing a constant supply of plankton and nutrients to the animals that inhabit their sides. They also cause upwelling of nutrient-rich waters toward the ocean surface.
https://www.fisheries.noaa.gov/new-england-mid-atlantic/habitat-conservation/northeast-canyons-and-seamounts-marine-national

Continental shelves of northern latitudes are topographically very irregular and are characterized by lowlands along the coast, U-shaped troughs extending from shore to the shelf's edge, and a chain of banks along the outer edge of the shelf (Holtedahl, 1958). This type of shelf occurs off New England (fig. 1) and consists of the Gulf of Maine, a broad 90, 700-km2 lowland, and Georges Bank, which separates the gulf from the open ocean. Northeast and Great South Channels provide passageways from the Gulf of Maine to the Atlantic Ocean. Cape Cod Bay, Nantucket Sound, and Buzzards Bay make up smaller lowlands.
SEDIMENTARY FRAMEWORK OF THE WESTERN GULF OF MAINE AND THE SOUTHEASTERN MASSACHUSETTS OFFSHORE AREA, R. N. 0LDALE, ELAZAR U CHUPI, 2 and K. E. Prada, Library of Congress catalog-card No. 72-600378 (1973)

Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation1. However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work2,3,4,5 has suggested that deep-water upwelling may occur along the ocean’s sloping seafloor; however, evidence has, so far, been indirect. Here we show vigorous near-bottom upwelling across isopycnals at a rate of the order of 100 metres per day, coupled with adiabatic exchange of near-boundary and interior fluid. These observations were made using a dye released close to the seafloor within a sloping submarine canyon, and they provide direct evidence of strong, bottom-focused diapycnal upwelling in the deep ocean. This supports previous suggestions that mixing at topographic features, such as canyons, leads to globally significant upwelling3,6,7,8. The upwelling rates observed were approximately 10,000 times higher than the global average value required for approximately 30 × 106 m3 s−1 of net upwelling globally9.
Wynne-Cattanach, B.L., Couto, N., Drake, H.F. et al. Observations of diapycnal upwelling within a sloping submarine canyon. Nature 630, 884–890 (2024). https://doi.org/10.1038/s41586-024-07411-2

Salt Marshes

Salt marshes aggrade in quasi-equilibrium with sea level rise (SLR) via the accumulation of organic matter and mineral sediment, thereby maintaining marsh platform elevation within the tidal frame (e.g., Allen, 2000; Cahoon et al., 2019). External perturbations, such as an acceleration of relative SLR, can be compensated for by increased sediment delivery to the marsh platform. Increased inundation depth tends to augment sediment delivery as the associated longer flood duration increases time to trap suspended sediment (Day et al., 1999; Reed, 1990; Temmerman et al., 2003). In some cases, increased suspended sediment concentrations associated with land clearance has allowed marshes to recover from rapid SLR (Peck et al., 2020; Watson, 2004). In addition to increased mineral sediment delivery, there is some evidence that bioproductivity of low marsh grasses may increase with moderate increases in inundation, with subsequent vegetation drowning at higher levels of inundation inundation, especially among high marsh grass species (Kirwan & Guntenspergen, 2015; Payne et al., 2019; Snedden et al., 2015). Under moderate rates of relative SLR, marshes can persist for thousands of years by building vertically (Pederson et al., 2005; Redfield, 1972) and/or transgressing into uplands (Doyle et al., 2010; Fagherazzi et al., 2019; Rampino & Sanders, 1980). (Morris et al., 2002; Voss et al., 2013).

Yellen, B., Woodruff, J. D., Baranes, H. E., Engelhart, S. E., Geyer, W. R., Randall, N., & Griswold, F. R. (2023). Salt marsh response to inlet switch-induced increases in tidal inundation. Journal of Geophysical Research: Earth Surface, 128, e2022JF006815. https://doi. org/10.1029/2022JF006815

Unusual Drainage

The ~1700 groundwater level is assumed to be equal to mean tide level (el. 5.7).
Report on Groundwater Observation Wells, Vol. 1, Stone & Webster for City of Boston ISD, (April 1990).

All studies to date of the cause of grw drawdown attribute a significant influence to the local sewer systems.
Plans 1863 show extensive system constructed but as built and locations lost or destroyed, much settling, and so actual locations are “entirely a matter of conjecture.” “These sewers and drains were the beginning of the present maze of underground channels of which little or nothing is known but which form channels by or along which the groundwater can escape the sewers in which the gradient is at a sufficiently low elevation to help drain the area.”
Snow tracing loss of groundwater Boston 1936
“in the opinion of Mr Snow, the city was underlain by a maze of subterranean channels leading groundwater off to the harbor.”
Report on Groundwater Observation Wells, Vol. 1, Stone & Webster for City of Boston ISD, (April 1990).

“All of the early sewers were constructed on top of a 8-12 inch underdrain which as designed to collect and control groundwater during construction. These remain in place to this day and are capable of transporting significant quantities of groundwater.”
West Side Interceptor and Boston Marginal Conduit both impede flow of gw into Back Bay from the Charles river, and have the ability to transport water rapidly along their length via their underdrain system.
St James Ave gw causing foundation issues in Trinity Church in 1930s, and resolved by putting dam in sewers and then gw returned to normal, but dam requires maintenance & if it fails, gw falls.
Underground subways block gw flow and can act as sinks/drains to pull down
80% of Back Bay area is paved so only small amount of recharge possible
The West Side Interceptor, Boston Marginal Conduit, and Mill Dam effectively isolate the Boston Peninsula from significant recharge from the Charles River.
The Muddy Water is a gw source in the Fenway.
The largest source of localized gw recharge is leaking water mains. However, Boston is working to repair leaking pipes in order to minimize water loss, which would then remove essentially the only significant source of gw recharge in the area.
Report on Groundwater Observation Wells, Vol. 1, Stone & Webster for City of Boston ISD, (April 1990).

It should be noted that most soil samples were collected at depths at or near the groundwater table surface. Soil samples saturated with diesel fuel were not submitted for laboratory analysis. Therefore, it is reasonable to assume that diesel fuel saturated soils are present in the same horizontal and vertical distribution. In addition, as described in the previous section, product is likely migrating into the bedding materials of an on property 48-inch sewer line. As these materials carry product towards the north and south, the surrounding soil (in both the vadose and saturated zones) is likely becoming contaminated.
In addition, product appears to be migrating in a northerly direction along a large utility corridor (South Boston Interceptor Trench) in the vicinity of well SW-4. This utility corridor contains a 48-inch diameter sewer pipe owned by BWSC. This sewer pipe carries stormwater that is collected over a large portion of South Boston. The pipe is located between approximately 15 to 25 feet below grade and, as such, intersects the groundwater table in the area of product at Cabot Yard. Acting as a preferential pathway, the bedding materials of this large sewer line likely contain product and are influencing the shape of the plume.
After constructing the South Boston Haul Road and installing numerous utilities and underdrains, a preferential pathway was created south of Cabot Yard that likely acts as a sink. Therefore, as the 48- inch sewer line collects product and carries it via bedding materials towards the north and south, the groundwater sink created by the Haul Road draws the carried product from the sewer line's bedding materials into the Haul Road's stormwater collection system (presumably via underdrains).
Widett Circle Properties, Boston, MA, Prepared by VHB for MBTA, Phase I Initial Site Investigation, Tier Classification, & Phase II Scope of Work (Aug. 9 2024).

The significant reduction in the elevation of Boston’s groundwater is attributed to the sewer system intentionally capturing the City’s streams, creeks, and brooks and emptying the water into the Charles River or Harbor rather then the ground; a 80%+ paved surface preventing natural infiltration; the underdrain system in the old sewers which naturally collects whatever rain water might actually breach the surface and then redirect it to the river or ocean; extensive depressed and underground railways which both act as impediments and also sinks; and repairs made by City of Boston to leaking water mains as they were the only significant source of groundwater recharge.
Report on Groundwater Observation Wells, Vol. 1, Stone & Webster for City of Boston ISD, (April 1990).

Reference Data

Mass DEP: Groundwater Wells