History
Long after Leif Erikson was reputed to have explored the Charles River in the Eleventh Century, the waterway served early settlers as a convenient “highway” and as a site for settlements and flourishing industries.
The river continued as a prime avenue for large scale commercial shipping well into the Twentieth Century. Meanwhile, some 750 acres of Back Bay Tidal land was filled in between 1834 and 1884, followed by additional filling of 640 acres behind retaining walls along the Boston and Cambridge shores. Remaining, however, was a Tidal Estuary that extended nine miles inland to the Watertown Dam, thus creating obnoxious conditions emanating from the exposed mud flats twice daily at low tides.
Condemning the Estuary from an environmental standpoint the Board of Metropolitan Park Commissioners and the State Board of Health in 1884, reported:
“The banks of the river and the exposed flats have become from year to year more offensive until … people living near the stream have been exposed to the disagreeable and probably injurious emanations therefrom.”
The report called for a dam at the mouth of the river to keep the tides out of the basin and maintain a permanent basin level and a lock to allow large vessels access to the river regardless of tide levels. A subsequent report stated that “difficulties experienced in passing under the low bridges at high tides have combined to make boating and use of the stream by small steamboats unattractive and, in a measure, dangerous.”
No less compelling was the landscape architects’ vision of a fresh water basin and shoreline park for “working people, who would find refreshment on the public river bank … (and) playgrounds for children.” They also foresaw “a throughly pleasant mode of travel on roads built upon the boundaries of the proposed reservation for a continuous parkway from Waltham to the heart of Boston.”
Held out as an example was “the world renowned Alster Basin, the water park of the City of Hamburg (Germany).” In his inaugural address of 1891, Boston Mayor Mathews declared, “We have in this basin the opportunity for making the finest water park in the country.”
These glowing visions became a reality over the years following completion of the 1170 foot dam, boat lock, and sluices in 1908, and a highway atop the dam in 1910. One large lock was provided. The lock was 350 feet long, 45 feet wide, and 18 feet deep at low water. The site replaced Craigie Bridge, originally built as a toll bridge in 1809, connecting Cambridge and Leverett Street in Boston.
The new river basin was set at eight feet above low tides (elevation 108), allowing about six to eight hours at each tide for sluicing river discharge by gravity flow. Design of sluicing facilities was based on 10 percent in excess of flood flow records for a freshet of February 1886, the largest recorded flood up to that time.
The sluicing waterway area served adequately in controlling maximum basin levels in a range of elevation 109 to 110.2 until 1954, when Hurricane Carol, accompanied by heavy rain, flooded Storrow Drive because of its low elevation of 109.5. A year later, Hurricane Diane hit the Boston area with a 12-inch rainfall and the basin level reached 112.55. Basin flooding caused damage of nearly $6 million and estimated $24 million at today’s costs. Lack of pumping was the big problem, for flood waters could not be released from the basin into the harbor when tides reached basin level.
Meanwhile, pleasure boat passage had grown enormously - nearly triple the 6,254 recorded numbers in 1911, for all types of crafts - causing congestion and delays. Projections indicated growth to 40,000 passages. Saltwater intrusion into the basin through the old dam had become a pollution problem, and the specter of other big storms hovered over invaluable river front and Back Bay property.
Following extended controversy over the best remedy, construction of a new $58.7 million dam was started in 1974, by the U.S. Army Corps of Engineers in conjunction with the Metropolitan District Commission, and completed in late 1979.
New Charles River Dam
The New Charles River Dam is a multipurpose dam using locks and sluiceways to control the elevation of the Charles River Basin.
The locks - water tight compartments with gates at both ends which raise or lower boats to let them pass between bodies of water at different levels - serve dual purposes: they pass boats between Boston Harbor and the Charles River Basin, and they drain excess flood waters from the basin into the Harbor during flood conditions.
The New Charles River Dam features two recreational vessel locks, measuring 220 feet long by 22 feet wide, and one commercial lock with dimensions of 300 feet long by 40 feet wide. All three locks are operated 24 hours a day, year-round.
When a boat enters a lock from a lower water level, the lock gates close, and the lock fills to raise the boat. When the water in the lock reaches the level of the other side, the opposite gates open to let the boat proceed. If a boat enters from higher water, the process is reversed. Once boats enter the locks, they are secured to floats.
If tidal water is higher than the water level of the basin, then before the lock gates to the basin are opened, the extra water is pumped back into the “ocean side” of the dam until the water in the lock is leveled to basin height.
The lock gates are electrically actuated, hydraulically operated bascule type dams structured on a horizontal axis at the bottom of the steel grates. If necessary, the locks can open partially at both ends during low tides to drain excess flood waters into the Harbor.
Pumping Station
To supplement the natural gravitational drainage of the basin through slucieways, the New Charles River Dam features a pumping station which houses six vertical lift pumps, each capable of pumping 630,000 gallons or a combined four million gallons of basin water back into the Harbor each minute. Each pump is driven by a 2,700 horsepower Fairbanks Morse Diesel Engine.
During possible flood conditions, which occur when the basin level reaches two inches above the 108 constant maintained by the Metropolitan District Commission, the pumps at the New Charles River Dam have the pumping capacity to convey water at a rapid rate, back into the harbor, through the discharge pipes, or sluices.
The pumping station itself is 190 feet long, 85 feet wide, and 60 feet high. It is bordered on the south by the MDC Police Boat Facility and on the north by Paul Revere Landing Park. An overhead enclosed walkway connects the pump station with three standing stair towers and with the three navigational locks below. The walkway houses the control station for operating the locks and runs the full length of the pump house which contains the MDC Offices responsible for the overseeing operations of the Charles River and all other locks and drawbridge facilities.
Fishway
The fishway incorporated into the New Charles River Dam was designed to restore anadromous fish - those which leave the ocean to spawn in fresh water - to the Charles River Basin. Although the fishway was designed to reintroduce the American Shad to the river, other species including alewife, blueback herring, white perch, rainbow smelt, and American eels travel through it as well.
Built as a ladder, the fishway is a vertical slot-type reinforced concrete structure 144.83 feet long by 4 feet wide, with a tope elevation of 16.55 feet mean sea level. The ladder has 29 connecting pools with a false weir to attract fish and provide a jump for their entrance into the Charles River Basin. It also features an exit channel connecting pool 17 of the ladder to the basin. This channel provides gravity flow freshwater and a passageway to the basin whenever the tide is below elevation 104.6 MDC.
The fishway is operated 24 hours a day from March 1st to July 15th. Juvenile fish migrating downstream between June and October will move to the sea partially via the boat locks.
The fishway was designed and constructed by the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.
