Popponesset Bay System is a group of bays located at the towns of Mashpee (north & west) and Barnstable (east), on

Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer mont ...

Massachusetts Massachusetts (Massachusett: ''Muhsachuweesut Massachusett_writing_systems.html" ;"title="nowiki/> məhswatʃəwiːsət.html" ;"title="Massachusett writing systems">məhswatʃəwiːsət">Massachusett writing systems">məhswatʃəwiːsət'' En ...

with a southern shore bounded by water from

Nantucket Sound Nantucket Sound_(geography), Sound is a roughly triangular area of the Atlantic Ocean offshore from the U.S. state of Massachusetts. It is long and wide, and is enclosed by Cape Cod on the north, Nantucket on the south, and Martha's Vineyard on ...

. Popponesset Bay has the following tributary sub-embayments: *Ockway Bay *Shoestring Bay *Mashpee River Estuary *Pinquickset Cove The bay system is fed by the

Mashpee River The Mashpee River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 1, 2011 tidal river on Cape Cod in Mashpee, Massachusetts. The river arises in Mashpee and Wakeby Ponds, fl ...

and

Santuit River The Santuit River, also known as the Cotuit River, is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed April 1, 2011 river on the border between Mashpee and Cotuit, Massachusetts on Cap ...

. Popponesset Creek is not a tributary but rather connects with the bay on both ends and separates Popponesset Island from the mainland. The bay’s watershed is distributed among the towns of Mashpee, Barnstable and

Sandwich, Massachusetts Sandwich is a town in Barnstable County, Massachusetts, and is the oldest town on Cape Cod. The town motto is ''Post tot Naufracia Portus'', "after so many shipwrecks, a haven". The population was 20,259 at the 2020 census. History Cape Cod ...

. The town of Sandwich does have jurisdiction over land and associated land uses in the uppermost portions of the Popponesset Bay watershed. Portions of the Popponesset Bay watershed that exist within the Town of Sandwich are mostly situated above the

Mashpee and Wakeby Ponds Mashpee Pond and Wakeby Pond are adjoining ponds in Mashpee and Sandwich, Massachusetts. When considered together, these two ponds cover and constitute the largest freshwater pond on Cape Cod. This pair is deep at its deepest point. The F ...

. Popponesset Bay has experienced problems with

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

from high

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

loads in the

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...

and runoff from the watersheds. The present bay results from

tidal flooding Tidal flooding, also known as sunny day flooding or nuisance flooding, is the temporary inundation of low-lying areas, especially streets, during exceptionally high tide events, such as at full and new moons. The highest tides of the year may b ...

of drowned river valleys formed primarily by the Mashpee and Santuit Rivers as a result of a risen sea level. The Bay is separated from Nantucket Sound by Popponesset Peninsula, a barrier spit which extends from the southwestern shore and is mostly occupied by Popponesset Beach. Popponesset Beach is known to the locals as simply "The Spit." Popponesset Bay has a second beach in the form of a sand bar in the middle of the bay, which is submersed during high tide. This island is known as Low Tide Island. The bay exchanges tidal water with Nantucket Sound through a single maintained inlet. The shore to the north of the inlet has been stabilized with

riprap Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. ...

as has the heavily residential southern portion of Popponesset Beach. The current spit is significantly shorter than seen in the 1880

Barnstable County Barnstable County is a county located in the U.S. state of Massachusetts. At the 2020 census, the population was 228,996. Its shire town is Barnstable. The county consists of Cape Cod and associated islands (some adjacent islands are in Duk ...

survey. The village of Popponesset takes its name from these waters.

References

Massachusetts Estuaries Project
{{coord, 41, 35, 30, N, 70, 27, 33, W, display=title Barnstable, Massachusetts Bodies of water of Barnstable County, Massachusetts Estuaries of Massachusetts Estuaries of Barnstable County, Massachusetts Bays of Massachusetts Mashpee, Massachusetts