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Moshassuck River Watershed

Map of Moshassuck Watershed


The Moshassuck River watershed encompasses 15,139 acres, or approximately 23.6 square miles in the Northeastern Rhode Island municipalities of Lincoln, Smithfield, Central Falls, North Providence, Pawtucket and Providence.

The Moshassuck River begins in Lincoln, Rhode Island, and flows ten miles into Providence where it meets the Woonasquatucket River in Providence's Waterplace Park. At that point the waters of the two rivers combine to form the Providence River, which joins the waters of the Blackstone/Seekonk system, which flow to Narragansett Bay and the sea. Twelve combined sewer overflows discharge to the Moshassuck River watershed: 10 to the river directly, and 2 to the West River, a tributary of the Moshassuck.

Natural History

The neighborhood of the headwaters was named for the presence of calcium based rocks originally laid down as limestone and now metamorphosed into marble. This unique geologic condition creates dramatically different soil conditions than the mostly Granitic based soils that predominate in New England and the rest of the watershed.

The forest in the area of the headwaters is predominantly Oak and many of the trees are large. Stone walls are found in the woods, and the entry path is a former commuter rail line. Because of the calcium based soils, many unusual and rare plants are found on the preserve. People hike and jog on the trails and picnic by the water. Where the Moshassuck reaches Route 146 the Lime Rock quarry is located. Lime has been mined in the area for hundreds of years. One of the last remaining farms in the watershed is found in this area, but the suburbanization of Lincoln means that even this sector of the watershed is losing its rural character.

Modern History

The term "moshassuck" is a Native American word meaning "where the moose drink" or "moose hunting", referring to an abundance of moose in the wetlands that made up much of the Moshassuck River Valley. 

The modern history of the watershed starts with Roger Williams and his cohorts settling along the lower section of the Moshassuck in1636. The Roger Williams Spring Historic Site, just across the street from the Moshassuck River near downtown Providence, marks the site of the first water supply used by the settlers. The settler¹s farms were laid out on what is now College Hill, which parallels the lower river and the Providence River below the confluence with the Woonasquatucket River.

The Euro-Americans cut down and burned forests in order to build houses and create farm land. They also started the trend of draining wetlands to create dry land for farms, cities and docking facilities. By the end of the Revolutionary War, Providence had leaped over Newport and became the leading city in Rhode Island, with the Moshassuck River an integral part of what was going on. Small dams were built to power grain mills and sawmills, and with the coming of the Industrial Revolution larger dams and a canal were built upon the river.

As the population along the Moshassuck increased the river came to be used as a sewer for human wastes. As the mills along the river grew in size and number, more industrial wastes poured into the river. The initial efforts to build a sewage system in Providence in the late 19th Century came about because Moshassuck River pollution had caused cholera outbreaks in Providence. In the late 19th Century mills lined the river all the way to Saylesville, and people moved even further from the river, which was probably just as well, as its odor was as bad as the water was toxic. 

As the textile industry faded away in Rhode Island, and the manufacturers that supported it such as machine shops followed suit, less industrial pollution poured into the Moshassuck. The Clean Water Act of 1972 provided a further incentive for those businesses still in the watershed to clean up their emissions and for the municipalities to clean up the sewage. Today, although sewage overflows and stormwater runoff prevent the Moshassuck from being a swimmable and fishable river, and toxic chemicals and metals persist in the bottom sediments, it is safe to say the Moshassuck is cleaner than it has been in 150 years, and people along the lower Moshassuck are returning to the river.

Water Quality & Management

Water quality along the Moshassuck River varies considerably due to the variety of land uses near its banks. Visually, the waters are relatively clear near the headwaters but quickly degrade as the river courses through the down stream communities. Before the river reaches Providence the water is discolored and turbid.

On dry days, when one walks along the Moshassuck in Providence, the water looks fairly clear, allowing an all-too-vivid view of the trash on the bottom of the river. On rainy days the water is so laden with silts from storm water and Combined Sewer Overflow discharges that even where the river is only a few inches deep one can not see the bottom. Unfortunately, the available information does not give a complete picture of water quality in the watershed.


Recent water testing for Fecal Coliform bacteria conducted by Mark Hengen and his students from Johnson and Wales University found Fecal Coliform counts to be low during dry weather, suggesting that the water may be relatively clean in the upper part of the watershed. Additional water quality monitoring would be needed to accurately determine the condition of the water and the uses which can be safely experienced.


The 2004 303(d) list of impaired waters identifies the Moshassuck River Basin as impaired for pathogens and phosphorous. TMDL development is being planned for some water bodies in the Moshassuck River watershed.

The Citizens Bank River Rescue Study

The Citizens Bank River Rescue Study was conducted between 1990 and 1995. Many pollutants were monitored in several Rhode Island urban rivers including the Moshassuck. The study consisted of monthly field measurements of air and water temperature, dissolved oxygen, nutrients, pH and hardness. Laboratory analysis was performed at the University of Rhode Island which focused on nutrients, metals, hardness, and total suspended solids. 

The results of the study indicated that water quality in the Moshassuck River has improved over the last ten years (Nixon and Granger, 1995 and Pilson and Hunt, 1989). The River Rescue study showed that Dissolved Oxygen levels near the mouth of the river consistently exceeded the critical level (minimum level to sustain healthy fish) of 5 mg/l, however the sampling station upstream near the Bonanza Bus Lines Terminal fell well below the minimum levels needed to protect the ecosystem. Compared to the older studies the Moshassuck River had lower concentrations of nutrients, lead, copper, nickel, cadmium and chromium.

Storm Water

There were a total of 32 storm water outfalls identified in the Moshassuck River. The storm water discharge pipe (M24) which is located near the on ramp to I-95 North at the Smithfield Avenue interchange ranked highest for needing a retrofit solution on the Moshassuck River. The pipe drains an area of approximately 5 acres of roadway which handles more than 30,000 vehicles per day. The annual load of pollutants entering from this one discharge pipe is a staggering 92,000 pounds per year (Draft design study report "Storm Drain Retrofit Demonstration Project" July 1999, Crossman Engineering).

Combined Sewer Overflows (CSO)

The Moshassuck Watershed has 15 CSOs, 12 discharge to the Moshassuck and 3 flow to the West River. Approximately 2 billion gallons of raw sewage is discharged from Rhode Island's CSOs each year. 

Organizations & Links

Friends of the Moshassuck

Friends of the Moshassuck (FOTM) started in 1998 because the lower part of the river really needed some friends. One of their first projects was the restoration of Collyer Field, which was conducted with the help of EPA and Save the Bay. This Providence site now has an active tree planting program, and more restoration plans are udnerway.

FOTM also developed a vision of a greenway linking the restoration sites along the Moshassuck. FOTM has developed partnerships with many organizations, including the National Park Service, Groundwork Providence, the Woodlawn Neighborhood Association, the City of Pawtucket, Youthbuild in both Pawtucket and Providence, and other citizens along the river. Restoration efforts on the Moshassuck continue with the help of these partners. In addition, FOTM is in the process of developing canoe/kayak launches on Galego Ct Pond and Canada Pond with funding from the Rhode Island Foundation.

Greg Gerritt
37 6th St. Providence, RI 02906