Boston Water System

In the 1840s, the City of Boston (pop. 50,000) was faced with water quality and capacity problems. Jamaica Pond was lacking in capacity and becoming increasingly polluted causing several epidemics. Several disastrous fires could not be contained due to lack of delivery capacity. A pure water source had to be found elsewhere.

In 1845, the Cochituate Water Board began construction of a transmission system. A tributary of the Sudbury River was impounded, which created Lake Cochituate. Cochituate, with its 17 miles of watershed, 2 billion gallons of storage and yield of 10 mgd, became the cornerstone of the Boston water system. The Cochituate Aqueduct was completed to transport water to the Brookline Reservoir from which pipelines were constructed to small distribution reservoirs in all parts of the city. The first water from Lake Cochituate flowed into the Frog Pond on Boston Common in 1848 at a dedication ceremony which drew 100,000 people.

In 1870, the Mystic Lakes system in Winchester, Medford, and Arlington, which had been developed by Charlestown, was added to the Boston system when Charlestown was annexed. This lake system had a yield of 30 mgd from its 28 sqare mile watershed. One of the original water mains to Charlestown is still in service.

The Great Fire of 1872, the last city-wide fire, left no doubt about the inadequacy of Boston's water supply.

After the Irish Potato Famine of 1843-45, Boston grew rapidly and by 1870, its population exceeded 200,000 and consumed 17 mgd. Planners had not anticipated this rapid growth and had thought that the Cochituate system would be adequate for many years. The process of diverting water from a pure upland source was repeated.

In 1878, the mainstream of the Sudbury River was diverted via the Sudbury Aqueduct to the Chestnut Hill Reservoir. Between 1875 and 1898, seven major reservoirs were constructed in the Upper Sudbury River Watershed. The Sudbury and Cochituate Aqueducts were designed to operate by gravity to fill the Chestnut Hill and Brookline Reservoirs, both of which are at Elevation 134. The Cochituate and Sudbury Aqueducts were interconnected at Chestnut Hill. During this period, the following pressure zones were established: Boston Low Southern High Northern Low Northern High Origin of the Boston Low Pressure Zone A series of large diameter water mains were extended from the Chestnut Hill reservoir to parallel those from the Brookline Reservoir. The mains from these two reservoirs are still in service and constitute the Boston Low System. By the turn of the century, the Boston Low System was transferred to the Weston Reservoir at the 200 foot elevation. Chestnut Hill pumping station was needed to provide water to the southern high service areas. Origin of the Southern High Pressure Zone A high service pumping station was constructed in Chestnut Hill to lift water from the Chestnut Hill Reservoir to areas which could not be supplied by gravity. Water was pumped to the Waban Hill reservoir in Newton and the Fisher Hill reservoir in Brookline.

Origin of the Northern Low Pressure Zone Charlestown was annexed to Boston during this era and its waterworks was integrated into the system. Charlestown's Mystic Lakes supply was conveyed by gravity to a pump station located near the intersection of the Alewife Brook and Mystic Valley Parkways and pumped to a covered reservoir which still exists (although no longer in use) beneath the quadrangle of Tufts University. The Mystic Supply Mains remain today as part of the Northern Low System.

A low service pumping station was constructed at the Chestnut Hill reservoir. Twin 48-inch diameter pipelines, the East and West Spot Pond Supply mains, were constructed from this pump station to the Mystic Main and continued to Spot Pond. After more than 100 years, these mains remain today as the principal ones of the Northern Low System. Origin of the Northern High Pressure Zone When Spot Pond was added to the system, it was raised 16 feet in elevation and the stream that formerly fed it was diverted around its perimeter. Spot Pond was converted into a distribution reservoir supplied only by pipelines. A pump station was constructed at Spot Pond to pump water to the Fells Reservoir which established the pressure gradient for the Northern High System.

1897 - Wachusett Reservoir The Boston metropolitan area continued to grow rapidly through the 1890s. Indoor plumbing became commonplace. Planners had not foreseen this development and supply had become inadequate. At this time, the following water sources were considered: the Nashua River, Lake Winnipesaukee, Sebago Lake, and the Merrimac River. Under the leadership of Frederic Stearns, Chief Engineer of the Metropolitan Water Board, it was decided that the new water source should be gravity-operated and not require filtration.

In 1897, the Nashua River above the town of Clinton was impounded by the Wachusett Dam. Six and 1/2 square miles were flooded in the towns of Boylston, West Boylston, Clinton and Sterling. and its water conveyed by the Wachusett/Weston Aqueduct to Weston Reservoir and then by pipeline to the Chestnut Hill and Spot Pond Reservoirs. Work was completed in 1905 and the reservoir first filled in May 1908.

The Wachusett system was built to service the 29 municipalities within the 10 mile radius of the State House. At the time, the Wachusett Reservoir was the largest public water supply reservoir in the world. Water from the Wachusett Aqueduct could be released into the reservoirs of the Sudbury River system for transport to Boston via the Sudbury Aqueduct. Water from the Wachusett Reservoir could also flow through the new Sudbury Reservoir to the Weston Aqueduct. During this period, Chestnut Hill Resrvoir was the hub of the system.

1926-1946 - Ware River and Quabbin Reservoir - Quabbin Reservoir was Boston's fourth westward reach for a pure upland source of water that could be delivered by gravity and not require filtration.

Construction of the Quabbin required impoundment of the Swift River and the taking of the towns of Dana, Enfield, Greenwich, and Prescott. In 1926, construction began on the Wachusett-Colebrook Tunnel, which is now the eastern section of the Quabbin Tunnel. Surplus flow in the Ware River was diverted to the Wachusett Reservoir during eight high-water months of the year and increased the safe yield by 40 mgd.

During the 1930s, the Wachusett-Colebrook tunnel was extended to the Swift River. It is a two-way tunnel: water flows west from the Ware River to the Quabbin during the high-water months and then east from the Quabbin to Wachusett at other times of the year.

Construction on the Quabbin Reservoir began in 1936. Filling commenced on August 14, 1939 and was completed in 1946 when water first flowed over the spillway. The Quabbin Reservoir was filled with water from the Swift River and flood skimming from the Ware River during eight months of the year. At the time, the 412 billion gallon reservoir was the largest man-made reservoir in the world which was devoted solely to water supply.

Planners feel that the Quabbin will be sufficient to supply the metropolitan area at least until the year 2020.