Neponset River Estuary
Assessment
Lynn Ficarra
General Characteristics
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From Walter Baker Dam to Dorchester Bay1
7 km long2
25-250 m wide at low tide, up to 1 km at high tide2
Depth ranges from <2-4 m at low tide2
3 m tidal range3
Large portion of water in estuary
exchanged at each tide3
• Surface area 0.88 km2 at low tide,
2.17 km2 at high tide2
• River flow through dam 0.6-3.1 m3/s
Neponset River Estuary1
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Shallow
Tidally dominant2
Probably well-mixed
Vertical salinity
stratification unknown
• Total volume of water in
estuary unknown
• Bottom topography
unknown
Habitats
Salt marsh4
– Was dominated by native Smooth cordgrass (Spartina
alterniflora) and Saltmeadow cordgrass (Spartina patens)
– Now invasive Common reed (Phragmites australis)
Spartina alterniflora
Spartina patens
Phragmites australis
– Past dredging, loss of natives, opportunity for invasives to
move in5
Habitats cont.
• Mud flats2
• Intertidal: 29% non-vegetated2
Habitat cont.
• In 1991, estuary had 311.64 acres of wetlands5
– 25.92 acres of non-vegetated wetland
– 265.67 acres of salt marsh
– 20.05 acres of common reed marsh
• But what about today?
– All remaining salt marshes degraded7
• Sediment characters unknown
Organisms
• Anadromous fisheries4
– Rainbow smelt
American shad
– Herring
– American shad
• River dams shortened runs4 and pollution lead to declining
fish populations6
• Nursery4
• Hunting grounds4
Herring
Rainbow smelt
Residence Time2
• ≤1 day
Nutrient Limitation7
• Nitrogen limited
Conclusions
• A lot of missing data
• Outdated information
• Projects
– Remove dam to improve
fish populations
– Restore salt marshes
• Will eelgrass and oysters help?
References
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Breault R.F. 2011. Concentrations, Loads, and Sources of Polychlorinated
Biphenyls, Neponset River and Neponset River Estuary, Eastern Massachusetts.
U.S. Geological Survey Scientific Investigations Report 2011-5004, 143 p.
Gardner G.B., R.F. Chen, and A. Berry. 2005. High-resolution measurements of
chromophoric dissolved organic matter (CDOM) in the Neponset River Estuary,
Boston Harbor, MA. Marine Chemistry. Vol. 96:137-154.
Zhu J. and C.R. Olsen. 2009. Beryllium-7 atmospheric deposition and sediment
inventories in the Neponset River estuary, Massachusetts, USA. Journal of
Environmental Radioactivity. Vol. 100:192-197.
NepRWA. 2006. Neponset Salt Marsh Restoration. The Neponset River
Watershed Association. http://www.neponset.org/Restoration-SaltMarsh.htm
Tiner R.W., D.B. Foulis, C. Nichols, S. Schaller, D. Petersen, K. Andersen, and J.
Swords. 1998. Wetland Status and Recent Trends for the Neponset Watershed,
Massachusetts (1977-1991). U.S. Fish and Wildlife Service National Wetlands
Inventory Project Northeast Region. 32 p.
Massachusetts Government. 1998. Neponset River Subwatershed-River and
Estuary Segment Assessments. Boston Harbor Watershed 1999 Water Quality
Assessment Report. p. 87-188.
NepRWA. 2004. Neponset River Watershed 2004 Assessment Report.
Massachusetts Executive Office of Environmental Affairs. 56 p.