The Foster's Pond Dam
The Foster's Pond Dam, owned and maintained by the Foster's Pond Corporation, was restored by volunteers in 2006 and 2007. The 165-year-old dam, with its spillway buttressed by granite walls and the upstream face protected by crushed stone, is a neighborhood icon.
The dam functions as a "pocket park" where residents and visitors can enjoy easy Pond access and a splendid view. There is no parking at the dam itself, but on-street parking is allowed on Carter Lane a short distance away, and visitors utilize three or four informal spots along Rattlesnake Hill Road.
Fishing is allowed (a license, of course, is required), and visitors may launch their canoe, kayak or bass boat (electric motors are permitted, but gasoline-powered engines are prohibited).
Please treat the dam gently - don't drag your boat, don't dig anywhere on the dam, and leave the crushed stones in place, protecting the dam from erosion. And if you bring it in, take it out - don't leave litter, bait cans, or cigarette butts behind. To download the rules and safety information posted at the dam, click here.
IN AN EMERGENCY: IF YOU ARE PASSING BY AND SEE WATER FLOWING OVER RATTLESNAKE HILL ROAD OR WOBURN STREET, THAT COULD BE A SIGN OF A POTENTIAL OR ACTUAL FAILURE OF THE DAM. DO NOT ATTEMPT TO WALK, BIKE OR DRIVE THROUGH FLOWING WATER. IF YOU SEE NO TRAFFIC CONES OR DETOUR SIGNS, CALL 911 AND REPORT THE SITUATION.
Click here for the latest information on the Dam: drawdowns, maintenance, and current conditions
Historical and Legal Background
Without the Foster's Pond Dam, there wouldn't be much to Foster's Pond. Old pre-dam maps, show the Pond to be a small oval sitting roughly in the middle of where the Main Pond now lies.
Before the Foster's Pond Dam was built in the late 1850s, the Pond covered only 50 acres - less than half its present size. The shape of the natural pond, taken from an 1830 survey, is here superimposed on today's 120-acre water body. The dam is located at what today is the tip of the bill of the "flying duck."
The dam was built with a commercial purpose. The aim was to impound water upstream from the mills on the Shawsheen River in Ballardvale, so that when the Shawsheen was running low during summer dry spells, water from Foster's Pond could be released to keep the mills going. With that end in mind, the original dam featured a wooden spillway over large wooden gates which could be opened to let the water through.
The original dam had large wooden gates behind the waterfall underneath the wooden spillway, so that water could be released to keep mills on the Shawsheen River in Ballardvale running in dry weather. This 1910 photo provided courtesy of the Andover Historical Society.
The plan, however, had a basic flaw. When the Shawsheen River was low, so was Foster's Pond, and the dam wasn't large enough to hold sufficient water to make much difference to the power needs of downstream mills. But the dam itself was quite pretty - as was the enlarged Pond it created. So the dam lived on, but without any deep-pocket caretaker with an economic incentive to maintain it.
The dam truly is the reason for the existence of the Foster's Pond Corporation. Indeed, when the Corporation was formed in 1939, its purpose, first and foremost, as stated in its corporate charter, was to "maintain, repair and operate the dam regulating the flow of water from Foster's Pond." The dam was owned at the time by an aging Francis H. Foster.
 |
| For decades, State inspectors worried that the sides of the dam's spillway were too short to prevent high water from spreading over the top of the dam, eroding the earthen crest. In this 2003 photo, the placid flow gives no hint of the problem. |
He came under increasing pressure from State inspectors to improve the condition of his dam, and, as more and more people were purchasing summer "camps" around the Pond, he decided to turn the task over to the new property owners. The Corporation was formed to take the dam off his hands. And while the Corporation has expanded its Pond-protection mission, there wouldn't be much to protect without the dam, which remains a central focus of Corporation concern. It has been maintained, over the years, by the efforts of volunteers.
The Massachusetts Office of Dam Safety's electronic file on the dam, lists the dam as having a structural height of 11 feet, a hydraulic height of 7 feet, and a crest length of 150 feet.
The dam is classified by the State as a "Significant Hazard" dam, a classification which under State regulations applies to dams "located where failure may cause loss of life and damage home(s), industrial or commercial facilities, secondary highway(s) or railroad(s) or cause interruption of use or service of relatively important facilities."
A major safety improvement, completed in 2007, was the restoration of an emergency spillway (to the left of the bench), which will prevent high water from flooding over - and eroding - the top of the earthen dam. The emergency spillway also doubles as a ramp for launching canoes, kayaks, and boats with electric motors. Gasoline-powered craft are prohibited.
The dam is rated by the State as one of "intermediate size", based on its having a storage capacity of more than 50 acre-feet and less than 1000 acre-feet. The Foster's Pond Dam is listed as having a "normal" storage of 420 acre-feet and a "maximum" capacity of 550 acre-feet.
The dam is subject to state regulation, including regular inspections. The Corporation is responsible for maintaining the dam.
In 2002, the General Court enacted revisions of the laws relating to the inspection, registration, and reconstruction of dams. The new laws, set forth in M.G.L. c. 253, s. 44 to s. 50A, are enforced by the Office of Dam Safety in the Executive Office of Environmental Affairs' Department of Conservation and Recreation.
The Office of Dam Safety (which has only three engineers on its staff) published new regulations in November, 2005, contained in 302 C.M.R. 10:00. These regulations set out the requirements for constructing new dams as well as inspecting and maintaining existing dams. The new regulations also required the registration of all dams commencing in January, 2006, and the inspection of all dams by the end of 2006.
The 2006 inspection of the Foster's Pond Dam found it in poor condition and needing significant restoration. A massive effort by volunteers, in late 2006 and through much of 2007, changed the face of the dam. For a detailed account of the project, click here.
There are an estimated 3100 dams in Massachusetts. About 750 of them carry the same "significant hazard potential" label that applies to our dam. The classification is based on what would happen if a dam fails, not on the present condition of the dam or the likelihood that it will give way. Another 320 dams are categorized as "high hazard potential."
Vandalism of a dam, or interference with its operation, is a felony in Massachusetts. Under M.G.L. c. 266, s. 138, anyone who without authorization removes or vandalizes a stop log or any other part of a dam, or obstructs the flow of water out of a dam, can be imprisoned for up to five years.
Some other documents relating to the dam
Foster's Pond Dam Phase I Inspection/Evaluation Report. A 62-page report by GEI Consultants, Inc., on their November 5, 2021 State-mandated inspection. The dam was again rated in "satisfactory" condition.
Foster's Pond Dam Emergency Action Plan. The 43-page EAP, prepared by GEI Consultants, Inc., was first approved by the Office of Dam Safety in September 2019. It is updated annually in consultation with local emergency personnel. It provides emergency responders with detailed information about what areas would be flooded in the event of a catastrophic breach of the Foster's Pond Dam, and outlines who should be notified and what steps need to be taken.
Foster's Pond Dam Phase I Inspection/Evaluation Report. A 65-page report by GEI Consultants, Inc., on their December 6, 2016 State-mandated inspection. The dam was again rated in "satisfactory" condition.
Foster's Pond Dam Phase I Inspection/Evaluation Report. A 67-page report by GEI Consultants, Inc., on their November 15, 2011 State-mandated inspection. The dam was rated in "satisfactory" condition.
Foster's Pond Dam Follow-Up Inspection/Evaluation Report. A 37-page report by GEI Consultants, Inc., on their May 8, 2008 inspection, which followed intense volunteer efforts by the Foster's Pond Corporation to restore the dam and improve its safety.
Foster's Pond Dam Phase 1 Inspection Report. A 58-page report by GEI Consultants, Inc., on their November 10, 2006 State-mandated inspection.
Office of Dam Safety’s Electronic File on Foster’s Pond Dam (as of August 12, 2003). A one-page summary of our dam's condition in 2003.
Office of Dam Safety's list of codes used in its electronic file. Helpful in decoding the Electronic File.
Questions? Comments? Contact us at